A couple git commit mail issues

[Christian Persch <chpe gnome org>]

Hi;

I've noticed two more issues with the git commit mails:

- for file moves, the diff contains both the complete old file (-'d)
  and the complete new file (+'d), making the commit mails a) very
  large, and b) hard to spot if the file was changed in the move as well
[example:
http://mail.gnome.org/archives/svn-commits-list/2009-April/msg00589.html]

- diffs are also sent out for changes to po/*.po while svn commit
  mails omits the diff for these [example:
http://mail.gnome.org/archives/svn-commits-list/2009-April/msg02491.html]

This is a problem since just a couple of these large commits a
day can DoS someone's mailbox by overloading their quota (the 2nd
example above is over 3MB large!).

Regards,
	Christian