Remove unused import
Correct indent
#22315: Add test to capture the failure.
merge 3.4
#22315: Use technique outlined in test_file_util
#22315: Provide an actual directory during test invocation.
#22315: Use an existent directory for 'src' to trigger appropriate behavior.
#22315: Use advertised API for OSError
Merge with 3.4; Closes #22315