Merge branch 'rr/rebase-reflog-message-reword'

"git rebase [-i]" used to leave just "rebase" as its reflog message
for some operations. This rewords them to be more informative.

* rr/rebase-reflog-message-reword:
  rebase -i: use a better reflog message
  rebase: use a better reflog message

git-rebase--interactive.sh

@@ -864,8 +864,11 @@ comment_for_reflog start
 
 if test ! -z "$switch_to"
 then
+	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $switch_to"
 	output git checkout "$switch_to" -- ||
-		die "Could not checkout $switch_to"
+	die "Could not checkout $switch_to"
+
+	comment_for_reflog start
 fi
 
 orig_head=$(git rev-parse --verify HEAD) || die "No HEAD?"
@@ -1007,6 +1010,7 @@ has_action "$todo" ||
 
 test -d "$rewritten" || test -n "$force_rebase" || skip_unnecessary_picks
 
+GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name"
 output git checkout $onto || die_abort "could not detach HEAD"
 git update-ref ORIG_HEAD $orig_head
 do_rest

git-rebase.sh

@@ -542,7 +542,9 @@ then
 	if test -z "$force_rebase"
 	then
 		# Lazily switch to the target branch if needed...
-		test -z "$switch_to" || git checkout "$switch_to" --
+		test -z "$switch_to" ||
+		GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $switch_to" \
+			git checkout "$switch_to" --
 		say "$(eval_gettext "Current branch \$branch_name is up to date.")"
 		finish_rebase
 		exit 0
@@ -568,7 +570,9 @@ test "$type" = interactive && run_specific_rebase
 
 # Detach HEAD and reset the tree
 say "$(gettext "First, rewinding head to replay your work on top of it...")"
-git checkout -q "$onto^0" || die "could not detach HEAD"
+
+GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name" \
+	git checkout -q "$onto^0" || die "could not detach HEAD"
 git update-ref ORIG_HEAD $orig_head
 
 # If the $onto is a proper descendant of the tip of the branch, then

t/t3404-rebase-interactive.sh

@@ -926,6 +926,21 @@ test_expect_success 'rebase --edit-todo can be used to modify todo' '
 	test L = $(git cat-file commit HEAD | sed -ne \$p)
 '
 
+test_expect_success 'rebase -i produces readable reflog' '
+	git reset --hard &&
+	git branch -f branch-reflog-test H &&
+	git rebase -i --onto I F branch-reflog-test &&
+	cat >expect <<-\EOF &&
+	rebase -i (start): checkout I
+	rebase -i (pick): G
+	rebase -i (pick): H
+	rebase -i (finish): returning to refs/heads/branch-reflog-test
+	EOF
+	tail -n 4 .git/logs/HEAD |
+	sed -e "s/.*	//" >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'rebase -i respects core.commentchar' '
 	git reset --hard &&
 	git checkout E^0 &&