uu module on line 53 erroneously tries to catch an AttributeError
exception type.

            try:
                mode = os.stat(in_file).st_mode
            except AttributeError:
                pass

This is not correct since os.stat(), as far as I know, should raise
OSError exceptions only.
This would turn in an error in case we pass a "broken" symlink as
in_file argument.

You misunderstand. The try/except is there in case os.stat isn't defined 
or its result doesn't have a st_mode attribute. If the stat operation 
fails due to a problem with the file, there's not much point in proceeding 
since the subsequent open() call would fail the same way.