t7004: fix mistaken tag name

We have a series of tests which create signed tags with
various properties, but one test accidentally verifies a tag
from much earlier in the series.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Ben Toews <mastahyeti@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7004-tag.sh

@@ -1056,7 +1056,7 @@ test_expect_success GPG \
 	git tag -s -F sigblanknonlfile blanknonlfile-signed-tag &&
 	get_tag_msg blanknonlfile-signed-tag >actual &&
 	test_cmp expect actual &&
-	git tag -v signed-tag
+	git tag -v blanknonlfile-signed-tag
 '
 
 # messages with commented lines for signed tags: