Merge branch 'fc/remote-bzr'

* fc/remote-bzr:
  remote-bzr: avoid bad refs
  remote-bzr: convert all unicode keys to str
  remote-bzr: access branches only when needed
  remote-bzr: delay peer branch usage
  remote-bzr: iterate revisions properly
  remote-bzr: improve progress reporting
  remote-bzr: add option to specify branches
  remote-bzr: add custom method to find branches
  remote-bzr: improve author sanitazion
  remote-bzr: add support for shared repo
  remote-bzr: fix branch names
  remote-bzr: add support for bzr repos
  remote-bzr: use branch variable when appropriate
  remote-bzr: fix partially pushed merge
  remote-bzr: fixes for branch diverge
  remote-bzr: add support to push merges
  remote-bzr: always try to update the worktree
  remote-bzr: fix order of locking in CustomTree
  remote-bzr: delay blob fetching until the very end
  remote-bzr: cleanup CustomTree