histedit: make cleanupnode more robust
The goal of this function is to strip content out of the repository. We do not
really care if this content is visible or cleanup node not and we should proceed
anyway. None of the internal actions are subject to this, however, a third party
extension running arbitrary commands during histedit is affected by this.
http://mercurial.selenic.com/bts/issue1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..