tag: use OPT_CMDMODE
tag: use OPT_CMDMODE

This is just a demonstration of how the code would look like; I do
not think it is particularly easier to read than before myself.

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