tests: add more test of resolution of content-divergent changesets This patch adds test of resolution of content-divergent changesets when relocation is required and it leads to conflicts. The test shows that we are not doing the right thing. This will be fixed in upcoming patches.

evolvestate: store info about relocation while resolving content-divergence While resolving content-divergence when they are on different parents, we relocate one of the node to parent of another one and this can lead to conflicts sometimes. So we need to store information about that state in evolvestate so that we can use that when user does `hg evolve --continue` or `--stop` or `--abort`. Now that we make sure, we store the new other node in evolvestate, we fix the behavior of handling the relocated commit and merge the right changesets.

evolve: factor out logic to merge content divergent csets in separate fn This will help us in reusing the logic if we need to while doing evolve --continue.