bisect: fix memory leak in `find_bisection()`

`find_bisection()` rebuilds the commit list it is given by reversing it
and skipping uninteresting commits. The uninteresting list entries are
leaked. Free them to fix the leak.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bisect.c

@@ -379,8 +379,10 @@ void find_bisection(struct commit_list **commit_list, int *reaches,
 		unsigned flags = p->item->object.flags;
 
 		next = p->next;
-		if (flags & UNINTERESTING)
+		if (flags & UNINTERESTING) {
+			free(p);
 			continue;
+		}
 		p->next = last;
 		last = p;
 		if (!(flags & TREESAME))