Merge branch 'ld/git-p4-branches-and-labels'

Merge branch 'ld/git-p4-branches-and-labels'

* ld/git-p4-branches-and-labels:
  git-p4: label import fails with multiple labels at the same changelist
  git-p4: add test for p4 labels
  git-p4: importing labels should cope with missing owner
  git-p4: cope with labels with empty descriptions
  git-p4: handle p4 branches and labels containing shell chars