Merge branch 'nd/rebase-show-current-patch'

The new "--show-current-patch" option gives an end-user facing way
to get the diff being applied when "git rebase" (and "git am")
stops with a conflict.

* nd/rebase-show-current-patch:
  rebase: introduce and use pseudo-ref REBASE_HEAD
  rebase: add --show-current-patch
  am: add --show-current-patch

git-rebase.sh

@@ -46,6 +46,7 @@ abort!             abort and check out the original branch
 skip!              skip current patch and continue
 edit-todo!         edit the todo list during an interactive rebase
 quit!              abort but keep HEAD where it is
+show-current-patch! show the patch file being applied or merged
 "
 . git-sh-setup
 set_reflog_action rebase
@@ -183,6 +184,7 @@ You can run "git stash pop" or "git stash drop" at any time.
 }
 
 finish_rebase () {
+	rm -f "$(git rev-parse --git-path REBASE_HEAD)"
 	apply_autostash &&
 	{ git gc --auto || true; } &&
 	rm -rf "$state_dir"
@@ -247,7 +249,7 @@ do
 	--verify)
 		ok_to_skip_pre_rebase=
 		;;
-	--continue|--skip|--abort|--quit|--edit-todo)
+	--continue|--skip|--abort|--quit|--edit-todo|--show-current-patch)
 		test $total_argc -eq 2 || usage
 		action=${1##--}
 		;;
@@ -417,6 +419,10 @@ quit)
 edit-todo)
 	run_specific_rebase
 	;;
+show-current-patch)
+	run_specific_rebase
+	die "BUG: run_specific_rebase is not supposed to return here"
+	;;
 esac
 
 # Make sure no rebase is in progress