Refine test to work under Windows.

test/bespoke/skip_bad_files/test.py

@@ -26,7 +26,7 @@ def main():
     # Dredd should return non-zero, due to 'bad1.c' and 'bad2.c'
     assert result.returncode != 0
     error_output = result.stderr.decode('utf-8')
-    pattern = "The following files were not mutated due to compile-time errors; see above for details:\n  [^\s]+bad1\.c\n  [^\s]+bad2\.c"
+    pattern = "The following files were not mutated due to compile-time errors; see above for details:\s+[^\s]+bad1\.c\s+[^\s]+bad2\.c"
     match = re.search(pattern, error_output)
     assert match is not None
     dictionary = json.load(open('info.json'))