builtin-remote: prune remotes correctly that were added with --mirror

This adds special handling for mirror remotes.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-remote.c

@@ -396,12 +396,22 @@ static int show_or_prune(int argc, const char **argv, int prune)
 
 		if (prune) {
 			struct strbuf buf;
+			int prefix_len;
 
 			strbuf_init(&buf, 0);
+			if (states.remote->fetch_refspec_nr == 1 &&
+					states.remote->fetch->pattern &&
+					!strcmp(states.remote->fetch->src,
+						states.remote->fetch->dst))
+				/* handle --mirror remote */
+				strbuf_addstr(&buf, "refs/heads/");
+			else
+				strbuf_addf(&buf, "refs/remotes/%s/", *argv);
+			prefix_len = buf.len;
+
 			for (i = 0; i < states.stale.nr; i++) {
-				strbuf_reset(&buf);
-				strbuf_addf(&buf, "refs/remotes/%s/%s", *argv,
-						states.stale.items[i].path);
+				strbuf_setlen(&buf, prefix_len);
+				strbuf_addstr(&buf, states.stale.items[i].path);
 				result |= delete_ref(buf.buf, NULL);
 			}
 

t/t5505-remote.sh

@@ -128,4 +128,20 @@ test_expect_success 'prune' '
 	 ! git rev-parse refs/remotes/origin/side)
 '
 
+test_expect_success 'add --mirror && prune' '
+	(mkdir mirror &&
+	 cd mirror &&
+	 git init &&
+	 git remote add --mirror -f origin ../one) &&
+	(cd one &&
+	 git branch -m side2 side) &&
+	(cd mirror &&
+	 git rev-parse --verify refs/heads/side2 &&
+	 ! git rev-parse --verify refs/heads/side &&
+	 git fetch origin &&
+	 git remote prune origin &&
+	 ! git rev-parse --verify refs/heads/side2 &&
+	 git rev-parse --verify refs/heads/side)
+'
+
 test_done