treewide: buildPhase="true" -> dontBuild=true

pkgs/applications/science/logic/mcy/default.nix

@@ -32,7 +32,7 @@ stdenv.mkDerivation {
   '';
 
   # the build needs a bit of work...
-  buildPhase = "true";
+  dontBuild = true;
   installPhase = ''
     mkdir -p $out/bin $out/share/mcy/{dash,scripts}
     install mcy.py      $out/bin/mcy      && chmod +x $out/bin/mcy

pkgs/applications/science/robotics/sumorobot-manager/default.nix

@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ wrapPython qt5.wrapQtAppsHook dos2unix ];
 
-  buildPhase = "true";
+  dontBuild = true;
 
   installPhase = ''
     mkdir -p $out/opt/sumorobot-manager

pkgs/data/themes/numix-solarized/default.nix

@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
     substituteInPlace Makefile --replace '$(DESTDIR)'/usr $out
   '';
 
-  buildPhase = "true";
+  dontBuild = true;
 
   installPhase = ''
     runHook preInstall

pkgs/development/libraries/science/math/rubiks/default.nix

@@ -19,7 +19,7 @@ stdenv.mkDerivation rec {
   '';
 
   # everything is done in `make install`
-  buildPhase = "true";
+  dontBuild = true;
 
   installFlags = [
     "PREFIX=$(out)"

pkgs/games/ckan/default.nix

@@ -16,7 +16,7 @@ stdenv.mkDerivation rec {
 
   libraries = lib.makeLibraryPath [ gtk2 curl ];
 
-  buildPhase = "true";
+  dontBuild = true;
 
   installPhase = ''
     install -m 644 -D $src $out/bin/ckan.exe

pkgs/tools/archivers/unp/default.nix

@@ -20,7 +20,7 @@ in stdenv.mkDerivation {
   };
 
   dontConfigure = true;
-  buildPhase = "true";
+  dontBuild = true;
   installPhase = ''
   mkdir -p $out/bin
   mkdir -p $out/share/man/man1