unamend: abort if commit was not created by `hg [un]amend`...
unamend: abort if commit was not created by `hg [un]amend`
`hg unamend` can currently undo any kind of rewrite, as long as it has
an obsmarker. However, that has quite unexpected results if you run it
after e.g. `hg rebase` (expecting it to behave like a generic `hg
undo` command), because it updates to the predecessor and leaves the
old changes in the working copy. I think it's better to allow `hg
unamend` only after `hg amend` (and after `hg unamend` because that's
documented as being supported).
Differential Revision:
https://phab.mercurial-scm.org/D12390
