git-p4: small improvements to user-preservation
git-p4: small improvements to user-preservation

. Slightly more paranoid checking of results from 'p4 change'
. Remove superfluous "-G"
. Don't modify the username if it is unchanged.
. Add a comment in the change template to show what is
  going to be done.

Signed-off-by: Luke Diamand <6b3799be4300e44489a08090123f3842e6419da5@diamand.org>
Acked-By: Pete Wyckoff <1a91d62f7ca67399625a4368a6ab5d4a3baa6073@padd.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git