evolve: make sure we consider all cases in if-else The part of code which is touched decides on evolution of merge changeset. We need proper handling of each case there, so before adding logic, let's add conditional for each case so that upcoming patches are easy to understand.

tests: add more cases about stabilization of an orphaned merge commit This patch adds three more cases related to stabilization of orphaned merge commits.

evolve: fix missing negation Spotted by Pulkit Goyal.

evolve: clarify message for ambiguous destination from split Message is a bit long, but should be less scary.