project: skip clone bundles when we've already initialized the object dir
project: skip clone bundles when we've already initialized the object dir

The clone bundle logic assumes there is a one-to-one mapping between the
projects/ and project-objects/ trees.  When using shared projects (where
we checkout different branches from the same project), this would lead us
to fetching the same clone bundle multiple times.  Automatically skip the
clone bundle logic if the project-objects/ dir already exists.

Bug: https://crbug.com/gerrit/10993
Change-Id: I82c6fa1faf8605fd56c104fcea2a43dd4eecbce4
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/298682
Reviewed-by: Michael Mortensen <668d7528ffdc223b4950b555aea5a48377d73cb0@google.com>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@google.com>

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