tests: test divergence created during interrupted rebase If a rebase runs into conflicts and the user somehow rewrites an unrebased commit in the rebase set while the rebase is interrupted, continuing it might result in divergence. It turns out that we decide to skip the commit. That seems to make sense, but it wasn't obvious to me that that's what we should do. Either way, this patch adds a test case for the current behavior. Differential Revision: https://phab.mercurial-scm.org/D10256