shelve: directly handle the initial parent alignment...
shelve: directly handle the initial parent alignment
Shelve is currently sub-contracting some of its work to the rebase extension.
In order to make shelve more independent and flexible we would like shelve to
handle the parent alignment directly.
After this change, we no longer need to use rebase in shelve.
Differential Revision:
https://phab.mercurial-scm.org/D3693
