remote-hg: fix commit messages

git fast-import expects an extra newline after the commit message data,
but we are adding it only on hg-git compat mode, which is why the
bidirectionality tests pass.

We should add it unconditionally.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/remote-helpers/git-remote-hg

@@ -326,6 +326,8 @@ def export_ref(repo, name, kind, head):
         else:
             modified, removed = get_filechanges(repo, c, parents[0])
 
+        desc += '\n'
+
         if mode == 'hg':
             extra_msg = ''
 
@@ -349,7 +351,6 @@ def export_ref(repo, name, kind, head):
                 else:
                     extra_msg += "extra : %s : %s\n" % (key, urllib.quote(value))
 
-            desc += '\n'
             if extra_msg:
                 desc += '\n--HG--\n' + extra_msg