diff --git a/pkgs/applications/audio/keyfinder/default.nix b/pkgs/applications/audio/keyfinder/default.nix
index 187d3a58b171..19433466ec3b 100644
--- a/pkgs/applications/audio/keyfinder/default.nix
+++ b/pkgs/applications/audio/keyfinder/default.nix
@@ -16,13 +16,10 @@ stdenv.mkDerivation rec {
 
   postPatch = ''
     substituteInPlace is_KeyFinder.pro \
-       --replace "keyfinder.0" "keyfinder" \
        --replace "-stdlib=libc++" "" \
        --replace "\$\$[QT_INSTALL_PREFIX]" "$out"
   '';
 
-  enableParallelBuilding = true;
-
   meta = with lib; {
     description = "Musical key detection for digital audio (graphical UI)";
     longDescription = ''
diff --git a/pkgs/applications/misc/archivy/default.nix b/pkgs/applications/misc/archivy/default.nix
index 4fa3d5cf4199..56260fa4f704 100644
--- a/pkgs/applications/misc/archivy/default.nix
+++ b/pkgs/applications/misc/archivy/default.nix
@@ -17,7 +17,6 @@ python3.pkgs.buildPythonApplication rec {
     substituteInPlace requirements.txt \
       --replace 'WTForms ==' 'WTForms >=' \
       --replace 'attrs == 20.2.0' 'attrs' \
-      --replace 'beautifulsoup4 ==' 'beautifulsoup4 >=' \
       --replace 'elasticsearch ==' 'elasticsearch >=' \
       --replace 'python_dotenv ==' 'python_dotenv >=' \
       --replace 'python_frontmatter == 0.5.0' 'python_frontmatter' \
diff --git a/pkgs/applications/networking/cluster/octant/default.nix b/pkgs/applications/networking/cluster/octant/default.nix
index 4eb2bf78b54a..ebf3cb417d69 100644
--- a/pkgs/applications/networking/cluster/octant/default.nix
+++ b/pkgs/applications/networking/cluster/octant/default.nix
@@ -25,7 +25,6 @@ stdenv.mkDerivation rec {
     x86_64-darwin = "0y2qjdlyvhrzwg0fmxsr3jl39kd13276a7wg0ndhdjfwxvdwpxkz";
   };
 
-  doBuild = false;
   doCheck = false;
 
   installPhase = ''
diff --git a/pkgs/applications/science/misc/foldingathome/control.nix b/pkgs/applications/science/misc/foldingathome/control.nix
index 832c63117591..1430881a3f08 100644
--- a/pkgs/applications/science/misc/foldingathome/control.nix
+++ b/pkgs/applications/science/misc/foldingathome/control.nix
@@ -35,8 +35,6 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ fahviewer python ];
 
-  doBuild = false;
-
   unpackPhase = ''
     dpkg-deb -x ${src} ./
   '';
diff --git a/pkgs/applications/version-management/git-and-tools/legit/default.nix b/pkgs/applications/version-management/git-and-tools/legit/default.nix
index 7dbdd6071a57..df2866527115 100644
--- a/pkgs/applications/version-management/git-and-tools/legit/default.nix
+++ b/pkgs/applications/version-management/git-and-tools/legit/default.nix
@@ -16,10 +16,8 @@ python3Packages.buildPythonApplication rec {
     six
   ];
 
-  # Prevent tests from trying to create configuration in /homeless-shelter.
-  preCheck = ''
-    export HOME=$PWD/test-home
-  '';
+  # no tests
+  doCheck = false;
 
   meta = with lib; {
     homepage = "https://github.com/frostming/legit";
diff --git a/pkgs/applications/video/vcs/default.nix b/pkgs/applications/video/vcs/default.nix
index 83b49c075784..4998797fcf3a 100644
--- a/pkgs/applications/video/vcs/default.nix
+++ b/pkgs/applications/video/vcs/default.nix
@@ -18,7 +18,6 @@ stdenv.mkDerivation {
   unpackCmd = "mkdir src; cp $curSrc src/vcs";
   patches = [ ./fonts.patch ];
   nativeBuildInputs = [ makeWrapper ];
-  doBuild = false;
 
   inherit dejavu_fonts;
   installPhase = ''
diff --git a/pkgs/development/interpreters/gauche/default.nix b/pkgs/development/interpreters/gauche/default.nix
index 75a931c55629..86dc7d666d2b 100644
--- a/pkgs/development/interpreters/gauche/default.nix
+++ b/pkgs/development/interpreters/gauche/default.nix
@@ -1,5 +1,5 @@
 { stdenv, lib, fetchFromGitHub, autoreconfHook, gaucheBootstrap, pkg-config, texinfo
-,  libiconv, gdbm, openssl, zlib, mbedtls, cacert }:
+, libiconv, gdbm, openssl, zlib, mbedtls, cacert }:
 
 stdenv.mkDerivation rec {
   pname = "gauche";
@@ -45,5 +45,6 @@ stdenv.mkDerivation rec {
     maintainers = with maintainers; [ mnacamura ];
     license = licenses.bsd3;
     platforms = platforms.unix;
+    broken = stdenv.isDarwin;
   };
 }
diff --git a/pkgs/development/libraries/rocclr/default.nix b/pkgs/development/libraries/rocclr/default.nix
index 9337680f55c7..278fdecc1a67 100644
--- a/pkgs/development/libraries/rocclr/default.nix
+++ b/pkgs/development/libraries/rocclr/default.nix
@@ -32,11 +32,8 @@ stdenv.mkDerivation rec {
 
   prePatch = ''
     substituteInPlace CMakeLists.txt \
-      --replace 'set(ROCCLR_EXPORTS_FILE "''${CMAKE_CURRENT_BINARY_DIR}/amdrocclr_staticTargets.cmake")' \
-        'set(ROCCLR_EXPORTS_FILE "''${CMAKE_INSTALL_LIBDIR}/cmake/amdrocclr_staticTargets.cmake")' \
       --replace 'set (CMAKE_LIBRARY_OUTPUT_DIRECTORY ''${CMAKE_CURRENT_BINARY_DIR}/lib)' \
-        'set (CMAKE_LIBRARY_OUTPUT_DIRECTORY ''${CMAKE_INSTALL_LIBDIR})' \
-      --replace 'find_library( OpenCL REQUIRED' 'find_library( OpenCL'
+        'set (CMAKE_LIBRARY_OUTPUT_DIRECTORY ''${CMAKE_INSTALL_LIBDIR})'
     substituteInPlace device/comgrctx.cpp \
       --replace "libamd_comgr.so" "${rocm-comgr}/lib/libamd_comgr.so"
   '';
diff --git a/pkgs/development/python-modules/apache-airflow/default.nix b/pkgs/development/python-modules/apache-airflow/default.nix
index ca2cb03f9672..705b7b721f8f 100644
--- a/pkgs/development/python-modules/apache-airflow/default.nix
+++ b/pkgs/development/python-modules/apache-airflow/default.nix
@@ -143,11 +143,9 @@ buildPythonPackage rec {
       --replace "flask-appbuilder>=1.12.5, <2.0.0" "flask-appbuilder" \
       --replace "flask-admin==1.5.3" "flask-admin" \
       --replace "flask-login>=0.3, <0.5" "flask-login" \
-      --replace "pendulum==1.4.4" "pendulum" \
       --replace "cached_property~=1.5" "cached_property" \
       --replace "dill>=0.2.2, <0.3" "dill" \
       --replace "configparser>=3.5.0, <3.6.0" "configparser" \
-      --replace "jinja2>=2.10.1, <2.11.0" "jinja2" \
       --replace "colorlog==4.0.2" "colorlog" \
       --replace "funcsigs==1.0.0" "funcsigs" \
       --replace "flask-swagger==0.2.13" "flask-swagger" \
diff --git a/pkgs/development/python-modules/deform/default.nix b/pkgs/development/python-modules/deform/default.nix
index bc84df26a278..5698dcbe491b 100644
--- a/pkgs/development/python-modules/deform/default.nix
+++ b/pkgs/development/python-modules/deform/default.nix
@@ -11,11 +11,6 @@ buildPythonPackage rec {
     sha256 = "1e912937650c1dbb830079dd9c039950762a230223a567740fbf1b23f1090367";
   };
 
-  postPatch = ''
-    substituteInPlace setup.py \
-      --replace "iso8601<=0.1.11" iso8601
-  '';
-
   propagatedBuildInputs = [
     chameleon
     colander
diff --git a/pkgs/development/python-modules/doit/default.nix b/pkgs/development/python-modules/doit/default.nix
index 36cd0b0ee185..4ceb8e71f648 100644
--- a/pkgs/development/python-modules/doit/default.nix
+++ b/pkgs/development/python-modules/doit/default.nix
@@ -25,6 +25,9 @@ buildPythonPackage rec {
     ++ lib.optional stdenv.isLinux pyinotify
     ++ lib.optional stdenv.isDarwin macfsevents;
 
+  # hangs on darwin
+  doCheck = !stdenv.isDarwin;
+
   checkInputs = [ mock pytestCheckHook ];
 
   disabledTests = [
diff --git a/pkgs/development/python-modules/dufte/default.nix b/pkgs/development/python-modules/dufte/default.nix
index dcf2896bba52..d1c9680cb7b9 100644
--- a/pkgs/development/python-modules/dufte/default.nix
+++ b/pkgs/development/python-modules/dufte/default.nix
@@ -6,6 +6,7 @@
 , importlib-metadata
 , matplotlib
 , numpy
+, exdown
 , pytestCheckHook
 }:
 
@@ -32,12 +33,9 @@ buildPythonPackage rec {
     mkdir -p $HOME/.matplotlib
     echo "backend: ps" > $HOME/.matplotlib/matplotlibrc
   '';
-  checkInputs = [ pytestCheckHook ];
+
+  checkInputs = [ exdown pytestCheckHook ];
   pythonImportsCheck = [ "dufte" ];
-  pytestFlagsArray = [
-    # we don't have the "exdown" package (yet)
-    "--ignore=test/test_readme.py"
-  ];
 
   meta = with lib; {
     description = "Clean matplotlib plots";
diff --git a/pkgs/development/python-modules/exdown/default.nix b/pkgs/development/python-modules/exdown/default.nix
new file mode 100644
index 000000000000..17cab3fe55fb
--- /dev/null
+++ b/pkgs/development/python-modules/exdown/default.nix
@@ -0,0 +1,24 @@
+{ lib, buildPythonPackage, fetchPypi, pythonOlder
+, importlib-metadata }:
+
+buildPythonPackage rec {
+  pname = "exdown";
+  version = "0.7.1";
+  format = "pyproject";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "sha256-vnSso3vmPIjX7JX+NwoxguwqwPHocJACeh5H0ClPcUI=";
+  };
+
+  propagatedBuildInputs = lib.optionals (pythonOlder "3.8") [ importlib-metadata ];
+
+  pythonImportsCheck = [ "exdown" ];
+
+  meta = with lib; {
+    description = "Extract code blocks from markdown";
+    homepage = "https://github.com/nschloe/exdown";
+    license = licenses.mit;
+    maintainers = with maintainers; [ SuperSandro2000 ];
+  };
+}
diff --git a/pkgs/development/python-modules/git-sweep/default.nix b/pkgs/development/python-modules/git-sweep/default.nix
index 2b17a46190b6..2d7da28535cf 100644
--- a/pkgs/development/python-modules/git-sweep/default.nix
+++ b/pkgs/development/python-modules/git-sweep/default.nix
@@ -15,6 +15,11 @@ buildPythonPackage rec {
 
   propagatedBuildInputs = [ GitPython ];
 
+  # no tests
+  doCheck = false;
+
+  pythonImportsCheck = [ "gitsweep" ];
+
   meta = with lib; {
     description = "A command-line tool that helps you clean up Git branches";
     homepage = "https://github.com/arc90/git-sweep";
diff --git a/pkgs/development/python-modules/nbdime/default.nix b/pkgs/development/python-modules/nbdime/default.nix
index 1de21f3511a4..299cfc87024c 100644
--- a/pkgs/development/python-modules/nbdime/default.nix
+++ b/pkgs/development/python-modules/nbdime/default.nix
@@ -12,7 +12,7 @@
 , tabulate
 , nbformat
 , jsonschema
-, pytest
+, pytestCheckHook
 , colorama
 , pygments
 , tornado
@@ -40,7 +40,16 @@ buildPythonPackage rec {
     jsonschema
     mock
     tabulate
-    pytest
+    pytestCheckHook
+  ];
+
+  disabledTests = [
+    "test_apply_filter_no_repo"
+    "test_diff_api_checkpoint"
+    "test_filter_cmd_invalid_filter"
+    "test_inline_merge"
+    "test_interrogate_filter_no_repo"
+    "test_merge_input_strategy_inline_source_conflict"
   ];
 
   nativeBuildInputs = [ setuptools_scm ];
diff --git a/pkgs/development/python-modules/pyslurm/default.nix b/pkgs/development/python-modules/pyslurm/default.nix
index a113314aa403..abb85930e40e 100644
--- a/pkgs/development/python-modules/pyslurm/default.nix
+++ b/pkgs/development/python-modules/pyslurm/default.nix
@@ -22,6 +22,7 @@ buildPythonPackage rec {
     description = "Python bindings to Slurm";
     license = licenses.gpl2;
     maintainers = with maintainers; [ bhipple ];
+    platforms = platforms.linux;
     broken = true;  # still needs slurm-19.05, but nixpkgs has slurm-20+ now
   };
 }
diff --git a/pkgs/development/python-modules/skein/skeinrepo.nix b/pkgs/development/python-modules/skein/skeinrepo.nix
index 85b4f19c8f73..d7bdef56ebe3 100644
--- a/pkgs/development/python-modules/skein/skeinrepo.nix
+++ b/pkgs/development/python-modules/skein/skeinrepo.nix
@@ -7,8 +7,6 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ maven ] ++ lib.optional stdenv.isLinux autoPatchelfHook;
 
-  doBuild = false;
-
   installPhase = ''
     mkdir -p $out
 
diff --git a/pkgs/development/python-modules/somajo/default.nix b/pkgs/development/python-modules/somajo/default.nix
index 11d0c02dfc84..54cd9beede3d 100644
--- a/pkgs/development/python-modules/somajo/default.nix
+++ b/pkgs/development/python-modules/somajo/default.nix
@@ -1,4 +1,4 @@
-{ pkgs, lib, fetchFromGitHub, buildPythonPackage, isPy3k, regex }:
+{ lib, stdenv, fetchFromGitHub, buildPythonPackage, isPy3k, regex }:
 
 buildPythonPackage rec {
   pname = "SoMaJo";
@@ -14,6 +14,9 @@ buildPythonPackage rec {
 
   propagatedBuildInputs = [ regex ];
 
+  # loops forever
+  doCheck = !stdenv.isDarwin;
+
   meta = with lib; {
     description = "Tokenizer and sentence splitter for German and English web texts";
     homepage = "https://github.com/tsproisl/SoMaJo";
diff --git a/pkgs/development/tools/fdroidserver/default.nix b/pkgs/development/tools/fdroidserver/default.nix
index 1b0c44f57548..2cc5e6b7ca5c 100644
--- a/pkgs/development/tools/fdroidserver/default.nix
+++ b/pkgs/development/tools/fdroidserver/default.nix
@@ -49,6 +49,9 @@ python.pkgs.buildPythonApplication rec {
     ruamel_yaml
   ];
 
+  # no tests
+  doCheck = false;
+
   meta = with lib; {
     homepage = "https://f-droid.org";
     description = "Server and tools for F-Droid, the Free Software repository system for Android";
diff --git a/pkgs/development/tools/git-repo-updater/default.nix b/pkgs/development/tools/git-repo-updater/default.nix
index dbf83677999a..d78972aa07bd 100644
--- a/pkgs/development/tools/git-repo-updater/default.nix
+++ b/pkgs/development/tools/git-repo-updater/default.nix
@@ -12,6 +12,9 @@ buildPythonApplication rec {
 
   propagatedBuildInputs = [ colorama GitPython ];
 
+  # no tests
+  doCheck = false;
+
   meta = with lib; {
     description = "Easily update multiple Git repositories at once";
     homepage = "https://github.com/earwig/git-repo-updater";
diff --git a/pkgs/servers/tautulli/default.nix b/pkgs/servers/tautulli/default.nix
index c7e88eb0c463..61f9c7851855 100644
--- a/pkgs/servers/tautulli/default.nix
+++ b/pkgs/servers/tautulli/default.nix
@@ -15,8 +15,6 @@ buildPythonApplication rec {
     sha256 = "QHpVIOtGFzNqAEcBCv48YWO4pYatbTe/CWwcwjbj+34=";
   };
 
-  doBuild = false;
-
   installPhase = ''
     mkdir -p $out/bin $out/libexec/tautulli
     cp -R contrib data lib plexpy Tautulli.py $out/libexec/tautulli
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 86bb0a3fc92d..e50d1bbbd148 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -2105,6 +2105,8 @@ in {
 
   ewmh = callPackage ../development/python-modules/ewmh { };
 
+  exdown = callPackage ../development/python-modules/exdown { };
+
   exchangelib = callPackage ../development/python-modules/exchangelib { };
 
   execnet = callPackage ../development/python-modules/execnet { };