In the case of pulling changes of a topic which is shared by multiple
repos, if the target source tree doesn't contain all of those repos,
the script will fail to apply changes.
Introduce a new argument, --ignore-unknown-changes, which ignores
changes whose repo is not in the manifest.xml.
Test: Pulling changes of a topic which is shared by multiple repos to
the source tree which contains part of those repos was done
successfully with the newly introduce argument.
Change-Id: Ie999121415bc1888b714d023ca251ad89701df11
Signed-off-by: Junghoon Jang <junghoonjang@google.com>
ac6afae3d6