bitbake: fetch2/git: Improve shallow clone tag fetching

Currently, tags are fetched as just a name, which works but means they're not
seen as tags by git commands like git describe. Instead, fetch them as refs/tags/XXX
which means such commands then work correctly.

(Bitbake rev: c1f30ad61f5e55beb377451887bbbc5cb569f2e5)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/git.py

@@ -634,7 +634,7 @@ class Git(FetchMethod):
             all_refs.append(line.split()[-1])
         extra_refs = []
         if 'tag' in ud.parm:
-            extra_refs.append(ud.parm['tag'])
+            extra_refs.append("refs/tags/" + ud.parm['tag'])
         for r in ud.shallow_extra_refs:
             if not ud.bareclone:
                 r = r.replace('refs/heads/', 'refs/remotes/origin/')