Sync with 1.8.3-rc0

Sync with 1.8.3-rc0

* master:
  Git 1.8.3-rc0
  remote-bzr: strip extra newline
  remote-bzr: tell bazaar to be quiet
  remote-bzr: store converted URL
  remote-hg: use hashlib instead of hg sha1 util
  remote-bzr: add support to push URLs
  remote-bzr: fix bad state issue
  remote-hg: remove extra check
  remote-helpers: trivial cleanups
  git add: avoid "-u/-A without pathspec" warning on stat-dirty paths
  Git 1.8.2.2
  t7409: do not use export X=Y
  test-hg-hg-git.sh: do not use export X=Y
  test-hg-bidi.sh: do not use export X=Y
  t9501: do not use export X=Y
  t9020: do not use export X=Y