[PATCH] replace: stop replace lookup when reaching a self-reference

[Mike Hommey <mh@glandium.org>]

It is possible to end up in situations where a replace ref points to
itself. In that case, it would seem better to stop the lookup rather
than try to follow the link infinitely and fail with "replace depth too
high".

Signed-off-by: Mike Hommey <mh@glandium.org>
---
 replace-object.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

I'm not entirely sure whether it's actually worth fixing. Arguably, `git
replace` should also avoid the footgun in the first place (although in
my case, it wasn't due to `git replace` itself).

diff --git a/replace-object.c b/replace-object.c
index e295e87943..97e479fe2b 100644
--- a/replace-object.c
+++ b/replace-object.c
@@ -66,7 +66,7 @@ const struct object_id *do_lookup_replace_object(struct repository *r,
 	while (depth-- > 0) {
 		struct replace_object *repl_obj =
 			oidmap_get(r->objects->replace_map, cur);
-		if (!repl_obj)
+		if (!repl_obj || oideq(cur, &repl_obj->replacement))
 			return cur;
 		cur = &repl_obj->replacement;
 	}
-- 
2.23.0