Fix failed merge of bpo-43288. (GH-24614)

Author: nascheme

Lib/test/test_importlib/fixtures.py

@@ -220,8 +220,6 @@ def setUp(self):
         self.fixtures.enter_context(tempdir_as_cwd())
         build_files(self.files)
 
-    def skip(self, reason):
-        raise unittest.SkipTest(reason)
 
 
 def build_files(file_defs, prefix=pathlib.Path()):
@@ -262,6 +260,9 @@ class FileBuilder:
     def unicode_filename(self):
         return FS_NONASCII or self.skip("File system does not support non-ascii.")
 
+    def skip(self, reason):
+        raise unittest.SkipTest(reason)
+
 
 def DALS(str):
     "Dedent and left-strip"