Merge branch 'dd/rebase-merge-reserves-onto-label'

The logic to avoid duplicate label names generated by "git rebase
--rebase-merges" forgot that the machinery itself uses "onto" as a
label name, which must be avoided by auto-generated labels, which
has been corrected.

* dd/rebase-merge-reserves-onto-label:
  sequencer: handle rebase-merges for "onto" message

sequencer.c

@@ -4567,10 +4567,15 @@ static int make_script_with_merges(struct pretty_print_context *pp,
 	strbuf_init(&state.buf, 32);
 
 	if (revs->cmdline.nr && (revs->cmdline.rev[0].flags & BOTTOM)) {
+		struct labels_entry *onto_label_entry;
 		struct object_id *oid = &revs->cmdline.rev[0].item->oid;
 		FLEX_ALLOC_STR(entry, string, "onto");
 		oidcpy(&entry->entry.oid, oid);
 		oidmap_put(&state.commit2label, entry);
+
+		FLEX_ALLOC_STR(onto_label_entry, label, "onto");
+		hashmap_entry_init(&onto_label_entry->entry, strihash("onto"));
+		hashmap_add(&state.labels, &onto_label_entry->entry);
 	}
 
 	/*

t/t3430-rebase-merges.sh

@@ -474,4 +474,25 @@ test_expect_success '--rebase-merges with commit that can generate bad character
 	git rebase --rebase-merges --force-rebase E
 '
 
+test_expect_success '--rebase-merges with message matched with onto label' '
+	git checkout -b onto-label E &&
+	git merge -m onto G &&
+	git rebase --rebase-merges --force-rebase E &&
+	test_cmp_graph <<-\EOF
+	*   onto
+	|\
+	| * G
+	| * F
+	* |   E
+	|\ \
+	| * | B
+	* | | D
+	| |/
+	|/|
+	* | C
+	|/
+	* A
+	EOF
+'
+
 test_done