Bisect reset: remove bisect refs that may have been packed.

If refs were ever packed in the middle of bisection, the bisect
refs were not removed from the "packed-refs" file.

This patch fixes this problem by using "git update-ref -d $ref $hash"
in "bisect_clean_state".

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-bisect.sh

@@ -351,7 +351,13 @@ bisect_reset() {
 
 bisect_clean_state() {
 	rm -fr "$GIT_DIR/refs/bisect"
-	rm -f "$GIT_DIR/refs/heads/bisect"
+
+	# There may be some refs packed during bisection.
+	git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* refs/heads/bisect |
+	while read ref hash
+	do
+		git update-ref -d $ref $hash
+	done
 	rm -f "$GIT_DIR/BISECT_LOG"
 	rm -f "$GIT_DIR/BISECT_NAMES"
 	rm -f "$GIT_DIR/BISECT_RUN"

t/t6030-bisect-porcelain.sh

@@ -71,6 +71,18 @@ test_expect_success 'bisect start with one bad and good' '
 	git bisect next
 '
 
+test_expect_success 'bisect reset removes packed refs' '
+	git bisect reset &&
+	git bisect start &&
+	git bisect good $HASH1 &&
+	git bisect bad $HASH3 &&
+	git pack-refs --all --prune &&
+	git bisect next &&
+	git bisect reset &&
+	test -z "$(git for-each-ref "refs/bisect/*")" &&
+	test -z "$(git for-each-ref "refs/heads/bisect")"
+'
+
 # $HASH1 is good, $HASH4 is bad, we skip $HASH3
 # but $HASH2 is bad,
 # so we should find $HASH2 as the first bad commit