Merge branch 'js/cherry-pick-usability'

* js/cherry-pick-usability:
  Teach commit about CHERRY_PICK_HEAD
  bash: teach __git_ps1 about CHERRY_PICK_HEAD
  Introduce CHERRY_PICK_HEAD
  t3507: introduce pristine-detach helper

contrib/completion/git-completion.bash

@@ -246,6 +246,8 @@ __git_ps1 ()
 				fi
 			elif [ -f "$g/MERGE_HEAD" ]; then
 				r="|MERGING"
+			elif [ -f "$g/CHERRY_PICK_HEAD" ]; then
+				r="|CHERRY-PICKING"
 			elif [ -f "$g/BISECT_LOG" ]; then
 				r="|BISECTING"
 			fi