Use non-existent channel to default ctest to use own image in update testing.

BUG=chromium-os:19471
TEST=Unittest + ctest by itself to see image used correctly

Change-Id: I17d8ac8d5ec909009dc91593b77b1f65112a88ed
Reviewed-on: http://gerrit.chromium.org/gerrit/6446
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Chris Sosa <sosa@chromium.org>
1 file changed