cmd/watcher: mirror without pulling refs from destination repo
cmd/watcher: mirror without pulling refs from destination repo

Change-Id: I36ff6c82a922be14c52b42bd05814edb7805790d
Reviewed-on: https://go-review.googlesource.com/14309
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/build,proppy/build,proppy/build,golang/build,proppy/build,golang/build,proppy/build,golang/build