Add "does not exist" message if repo is missing (e.g., nonexistent overlay).

BUG=chromium:345098
TEST=build factory toolkit

Change-Id: I16e1f76ab983dfef3184ac25d1d7c04e3bcf00b4
Reviewed-on: https://chromium-review.googlesource.com/187220
Reviewed-by: Jon Salz <jsalz@chromium.org>
Commit-Queue: Jon Salz <jsalz@chromium.org>
Tested-by: Jon Salz <jsalz@chromium.org>
1 file changed