fetch2/git: Dereference unresolved names with ls-remote

[Richard Purdie <richard.purdie@linuxfoundation.org>]

We need to deference names when trying to map them to commit IDs with
ls-remote. If we don't do this, a given commit might not show up
later in a specific branch. There appears to be no good reason not
to do this.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/bitbake/lib/bb/fetch2/git.py b/bitbake/lib/bb/fetch2/git.py
index cae1653..ed55f43 100644
--- a/bitbake/lib/bb/fetch2/git.py
+++ b/bitbake/lib/bb/fetch2/git.py
@@ -326,7 +326,7 @@ class Git(FetchMethod):
         else:
             username = ""
 
-        cmd = "%s ls-remote %s://%s%s%s %s" % \
+        cmd = "%s ls-remote %s://%s%s%s %s^{}" % \
               (ud.basecmd, ud.proto, username, ud.host, ud.path, ud.unresolvedrev[name])
         if ud.proto.lower() != 'file':
             bb.fetch2.check_network_access(d, cmd)