copytrace: use the full copytracing method if only drafts are involved This patch adds the functionality to use the full copytracing even if `experimental.copytrace = heuristics` in cases when drafts are involved. This is also a part of copytrace extension in fbext. This also adds tests which are also taken from fbext. .. feature:: The `heuristics` option for `experimental.copytrace` performs full copytracing if both source and destination branches contains non-public changsets only. Differential Revision: https://phab.mercurial-scm.org/D625