python3Packages.dbf: Workaround broken build on Darwin

Skip test that fails on case-insensitive filesystems pending an upstream
fix (see issue linked in code).

pkgs/development/python-modules/dbf/darwin.patch

@@ -0,0 +1,12 @@
+diff --git a/dbf/test.py b/dbf/test.py
+index 117f611..34a9507 100755
+--- a/dbf/test.py
++++ b/dbf/test.py
+@@ -4814,6 +4814,7 @@ def test_index_search(self):
+         self.assertEqual(sorted.index_search('jul', partial=True), 9)
+         self.assertTrue(sorted.index_search('jul', partial=True))
+ 
++    @unittest.skipIf(sys.platform == 'darwin', 'fails on case-insensitive filesystems')
+     def test_mismatched_extensions(self):
+         old_memo_name = self.dbf_table._meta.memoname
+         new_memo_name = old_memo_name[:-3] + 'Dbt'

pkgs/development/python-modules/dbf/default.nix

@@ -19,6 +19,9 @@ buildPythonPackage rec {
     hash = "sha256-MFEi1U0RNvrfDtV4HpvPgKTCibAh76z7Gnmj32IubYw=";
   };
 
+  # Workaround for https://github.com/ethanfurman/dbf/issues/48
+  patches = lib.optional python.stdenv.isDarwin ./darwin.patch;
+
   propagatedBuildInputs = [ aenum ];
 
   checkPhase = ''