rebase: improve invalid revisions filtering
- Filter rebasestate nullmerge and unrebased revision before considering
updating obsolete. This simplifies the handling of obsolete and make
it ignore unrebased revision rather than extinguishing them.
- Apply obsolete markers only if rebasestate is not empty, testing
rebasetarget was irrelevant.
doc generated with sphinx. tutorial exported using sphinxedhg
http://hg.piranha.org.ua/sphinxedhg/