repo: make --version always work
repo: make --version always work

We don't really care what the subcommand is set to when --version
output is requested, so stop enforcing it.  This fixes some weird
behavior like `repo --version version` fails, but `repo --version
help` works.

The new logic skips subcommand validation, so `repo --version asdf`
will still display the version output.  This matches git behavior,
and makes a bit of sense when we consider that the user really wants
to see the tool version, and probably doesn't care about anything
else on the command line.

Change-Id: I87454d473c2c8869344b3888a7affaa2e03f5b0f
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/312907
Reviewed-by: Xin Li <93465216fd46a440eb04b27d6e009aced8b0c153@google.com>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@google.com>

GerritCodeReview/git-repo,GerritCodeReview/git-repo,lewixliu/git-repo,couchbasedeps/git-repo,couchbasedeps/git-repo,lewixliu/git-repo