evolve: return the new replacement node to be stored in evolvestate While resolving phase-divergence, we can end up obsoleting the phase-divergent commit in favor of the public commit. Before this patch we return the node of public commit to store as a replacement of the phase-divergent commit. The above will not cause any problem till the time we use `hg evolve --abort` on an interrupted evolve which tries to strip the replacement nodes because it thinks that the replacements nodes are the ones which are created during the resolution and are new. Since we will be stripping a public node, `evolve --abort` will error out saying cannot strip public changeset, unable to abort evolve which is bad. We should make sure, replacements should only consist of new nodes formed. If the instablity is resolved by obsoleting in favour of old changeset, we should not store the old changeset in replacements in evolvestate.

evolve: don't make values of replacements dict lists There was inconsistency in code base related to the values stored in replacements dict in evolvestate. At some places we store a list, at some places we just store the nodeid. Let's make sure we store only the nodeid, not a list. If there are cases, when there are multiple replacements or changesets created during resolution, later patch will introduce storing temprevs in evolvestate which should be used.

tests: add a test file `--abort` flag while resolving phase-divergence This patch adds a new test file test-evolve-abort-phasediv.t which will contain tests for `hg evolve --abort` flag while resolving phase-divergence. There is a case in this test which does not work right which will be fixed in upcoming patches.

evolve: pass revisions as strings to commands.*() It's usually fine to pass integer revisions to e.g. commands.update(), but when directaccess is enabled, it attempts to parse it a revset, which fails.