tests: add test showing `hg evolve --stop` works fine with phase-divergence
This patch adds a new test file which contains test demonstrating that `--stop`
flag works well while resolving phase-divergence using `hg evolve`.
tests: rename the test file to add 'orphan' in the name
test-evolve-stop.t contains test for `hg evolve --stop` for orphan resolution
only. We also need to test the flag while resolving divergence. It will be good
if we have a test file for each type of instability.