obsolete: do not obsolete rebase --detach nullmerge revs Rebase state contains the changesets to rebase as well as 'nullmerge' entries used drive the merge strategy. These nullmerge were not rebased and should be ignored, and certainly not be marked obsolete.

evolve: fix relocate() with removed revision relocate() was not handling the case where the rebased revision was discarded and was raising when trying to update the phase of None.

test-obsolete-rebase.t: test --abort and --continue