Remove redundant check

bootstrap_attr_stack() also checks whether attr_stack is already set.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/attr.c b/attr.c
index b8ce158..ab30c81 100644
--- a/attr.c
+++ b/attr.c
@@ -565,8 +565,7 @@
 	 * .gitattributes in deeper directories to shallower ones,
 	 * and finally use the built-in set as the default.
 	 */
-	if (!attr_stack)
-		bootstrap_attr_stack();
+	bootstrap_attr_stack();
 
 	/*
 	 * Pop the "info" one that is always at the top of the stack.