request-pull: resurrect for-linus -> tags/for-linus DWIM

Older versions of Git before v1.7.10 did not DWIM

    $ git pull $URL for-linus

to the tag "tags/for-linus" and the users were required to say

    $ git pull $URL tags/for-linus

instead.  Because newer versions of Git works either way,
request-pull used to show tags/for-linus when asked

    $ git request-pull origin/master $URL for-linus

The recent updates broke this and in the output we see "for-linus"
without the "tags/" prefix.

As v1.7.10 is more than 2 years old, this should matter very little
in practice, but resurrecting it is very simple.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-request-pull.sh

@@ -118,6 +118,12 @@ then
 	status=1
 fi
 
+# Special case: turn "for_linus" to "tags/for_linus" when it is correct
+if test "$ref" = "refs/tags/$pretty_remote"
+then
+	pretty_remote=tags/$pretty_remote
+fi
+
 url=$(git ls-remote --get-url "$url")
 
 git show -s --format='The following changes since commit %H: