git-checkout: describe detached head correctly
git-checkout: describe detached head correctly

When you have a file called HEAD in the work tree, the code to report
where the HEAD is at when "git checkout $commit^0" is done triggered
unnecessary ambiguity checking.

Explicitly mark the command line with "--" and make it clear that we are
talking about a revision.

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