Missing import re

I don't even know how it magically worked, but the fact is the code was
correct, and ran OK without the import re.

lib/ansible/modules/extras/system/locale_gen.py

@@ -4,6 +4,7 @@
 import os
 import os.path
 from subprocess import Popen, PIPE, call
+import re
 
 DOCUMENTATION = '''
 ---