git-cl set_close: Don't fail on branches with no issue
git-cl set_close: Don't fail on branches with no issue

R=a30c74fa30536fe7ea81ed6dec202e35e149e1fd@chromium.org

Bug: 258661
Change-Id: Iee910d6d01df4c675523abdaf4e505364f94c4aa
Reviewed-on: https://chromium-review.googlesource.com/651233
Reviewed-by: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@chromium.org>
Commit-Queue: Aaron Gable <bbed39beedae4cdb499af742d2fcd6c63934d93b@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools