Stop watching the upstream attribute of subscribed manifest

The plugin will no longer update projects that are pegged to a specific
rev/hash with an upstream attribute.  Previously, the plugin will update
the snapshot manifest base on the upstream attribute even though the
manifest being monitored is pegged at a specific rev.

Change-Id: I5f36c27671872093b9a8d5c55cb921e17e9c6e83
1 file changed