builtin/replace: unset read_replace_refs

When checking to see if some objects are of the same type
and when displaying the type of objects, git replace uses
the sha1_object_info() function.

Unfortunately this function by default respects replace
refs, so instead of the type of a replaced object, it
gives the type of the replacement object which might
be different.

To fix this bug, and because git replace should work at a
level before replacement takes place, let's unset the
read_replace_refs global variable at the beginning of
cmd_replace().

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

builtin/replace.c

diff --git a/builtin/replace.c b/builtin/replace.c
index 9f3619a..1672870 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -174,6 +174,8 @@
 		OPT_END()
 	};
 
+	read_replace_refs = 0;
+
 	argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 
 	if (list && delete)

t/t6050-replace.sh

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index e1cc3b8..d0c62f7 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -306,7 +306,7 @@
 	test_cmp expected actual
 '
 
-test_expect_failure 'test --format full' '
+test_expect_success 'test --format full' '
 	{
 		echo "$H1 (commit) -> $BLOB (blob)" &&
 		echo "$BLOB (blob) -> $REPLACED (blob)" &&