rebase: warn about the correct tree's OID

This was a simple copy/paste error, and an obvious one at that: if we
cannot fill the tree descriptor, we should show an error message about
*that* tree, not another one.

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

Author: dscho

builtin/rebase.c

@@ -576,7 +576,8 @@ static int reset_head(struct object_id *oid, const char *action,
 	}
 
 	if (!reset_hard && !fill_tree_descriptor(&desc[nr++], &head_oid)) {
-		ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
+		ret = error(_("failed to find tree of %s"),
+			    oid_to_hex(&head_oid));
 		goto leave_reset_head;
 	}