tests: add tests for testing --abort while content-divergence resolution This patch adds a new test file with a very basic test of `--abort` on an interrupted evolve which was resolving content-divergence. Upcoming patches will add more rigourous tests.

evolve: fix storage of replacements and temprevs node in evolvestate The _completephaseivergent() was not respecting rules on how to store the new node ids created in evolvestate. The rules are: * store the temporary relocated commits in temprevs * store the final new commit in replacements This patch make sure we follow the above rules and also use the return value returned by _resolvephasedivergence(). The tests change demonstrates that we are all good now.