copies: properly match result during changeset centric copy tracing By filtering "during" the iteration we were excluding rename information that were not in the matched set but that file served as base information for the matched set. We now do all copy tracing matching at the end of the process to ensure we raise proper result. If we were aggregating information top down instead of bottom up we could do filtering during processing. However, we don't. Differential Revision: https://phab.mercurial-scm.org/D9585