Remove unnecessary usage of strncmp() in git-rev-list arg parsing.
Remove unnecessary usage of strncmp() in git-rev-list arg parsing.

Not only is it unnecessary, it incorrectly allows extraneous characters
at the end of the argument.

Junio noticed the --merge-order thing, and Jon points out that if we fix
that one, we should fix --show-breaks too.

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