Merge branch 'ob/revert-of-revert' into seen

Instead of "Revert "Revert "original"", give "Reapply "original""
as the title for a revert of a revert.

* ob/revert-of-revert:
  sequencer: beautify subject of reverts of reverts

3 files changed, 52 insertions, 0 deletions

diff --git a/Documentation/git-revert.txt b/Documentation/git-revert.txt
index d2e10d3dce..e8fa513607 100644
--- a/Documentation/git-revert.txt
+++ b/Documentation/git-revert.txt
@@ -31,6 +31,12 @@ both will discard uncommitted changes in your working directory.
 See "Reset, restore and revert" in linkgit:git[1] for the differences
 between the three commands.
 
+The command generates the subject 'Revert "<title>"' for the resulting
+commit, assuming the original commit's subject is '<title>'.  Reverting
+such a reversion commit in turn yields the subject 'Reapply "<title>"'.
+These can of course be modified in the editor when the reason for
+reverting is described.
+
 OPTIONS
 -------
 <commit>...::
diff --git a/sequencer.c b/sequencer.c
index 83d53a7bf6..82b34942bf 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -2253,6 +2253,8 @@ static int do_pick_commit(struct repository *r,
 	 */
 
 	if (command == TODO_REVERT) {
+		const char *orig_subject;
+
 		base = commit;
 		base_label = msg.label;
 		next = parent;
@@ -2260,6 +2262,18 @@ static int do_pick_commit(struct repository *r,
 		if (opts->commit_use_reference) {
 			strbuf_addstr(&msgbuf,
 				"# *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***");
+		} else if (skip_prefix(msg.subject, "Revert \"", &orig_subject)) {
+			if (skip_prefix(orig_subject, "Revert \"", &orig_subject)) {
+				/*
+				 * This prevents the generation of somewhat unintuitive (even if
+				 * not incorrect) 'Reapply "Revert "' titles from legacy double
+				 * reverts. Fixing up deeper recursions is left to the user.
+				 */
+				strbuf_addstr(&msgbuf, "Revert \"Reapply \"");
+			} else {
+				strbuf_addstr(&msgbuf, "Reapply \"");
+			}
+			strbuf_addstr(&msgbuf, orig_subject);
 		} else {
 			strbuf_addstr(&msgbuf, "Revert \"");
 			strbuf_addstr(&msgbuf, msg.subject);
diff --git a/t/t3515-revert-subjects.sh b/t/t3515-revert-subjects.sh
new file mode 100755
index 0000000000..4c231b48a5
--- /dev/null
+++ b/t/t3515-revert-subjects.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+test_description='git revert'
+
+. ./test-lib.sh
+
+test_expect_success 'fresh reverts' '
+	test_commit --no-tag A file1 &&
+	test_commit --no-tag B file1 &&
+	git revert --no-edit HEAD &&
+	echo "Revert \"B\"" > expect &&
+	git log -1 --pretty=%s > actual &&
+	test_cmp expect actual &&
+	git revert --no-edit HEAD &&
+	echo "Reapply \"B\"" > expect &&
+	git log -1 --pretty=%s > actual &&
+	test_cmp expect actual &&
+	git revert --no-edit HEAD &&
+	echo "Revert \"Reapply \"B\"\"" > expect &&
+	git log -1 --pretty=%s > actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'legacy double revert' '
+	test_commit --no-tag "Revert \"Revert \"B\"\"" file1 &&
+	git revert --no-edit HEAD &&
+	echo "Revert \"Reapply \"B\"\"" > expect &&
+	git log -1 --pretty=%s > actual &&
+	test_cmp expect actual
+'
+
+test_done