completion: For consistency, change "git rev-parse" to __gitdir calls
completion: For consistency, change "git rev-parse" to __gitdir calls

Signed-off-by: Ted Pavlic <46ab578353b0478abc71fa54796a76c10bbe41a8@tedpavlic.com>
Acked-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>
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