test & fix for mangled tagger names

[orestis]

I've found and fixed an issue where the tagger names where not parsed correctly.

The root cause was that the 'tagger' prefix was stripped before passed on to the parse_actor_and_date function, so the first name of the author was consumed by the RE instead. I've changed the code to pass the whole line to the parse_actor_and_date function, as it is done in git/objects/commit.py and it fixes the issue.

[Byron]

Hi Orestis,

Thanks for your fix and test, which appear to work fine. I wonder how the test-suite could not have noticed that issue, maybe I didn't test the tagger name specifically.

Thank you,
Sebastian