[PATCH 0 of 2] phase mouvement with rebase and graft

[alain.leufroy at logilab.fr]

These 2 changesets fix phase mouvement with rebase and add test for graft.

Rebase:
  The idea is to _try_ to keep source phase on rebase.

Draft:
  The idea is not to keep the phase of the cherry-picked changesets
  because::

 * draft is a copy if the "operations" made on the source changets while rebase is used to move
   changesets
 * draft allow to reorder changesets

What do you think about the draft behaviour? It shall be same for transplant.