tests: add more test of --stop while resolving content-divergence This tests the --stop flag when conflicts occur while relocating one of the divergent changesets.

evolve: strip the relocation commit on `hg evolve --stop` While resolving content-divergence on multiple parents, we relocate one of the commit on the parent of another one and then merge the divergent changesets. Merging can leads to conflicts, and if user does `hg evolve --stop`, we need to strip that relocated changeset too! This patch does that. Test changes demonstrates the fix.