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

By Luke Diamand * ld/git-p4-tags-and-labels: git p4: fix unit tests git p4: move verbose to base class git p4: Ignore P4EDITOR if it is empty git p4: Squash P4EDITOR in test harness git p4: fix-up "import/export of labels to/from p4" git p4: import/export of labels to/from p4 git p4: Fixing script editor checks