[ostree] refs: Add a missing `goto out` for error handling

[Colin Walters <walters src gnome org>]

commit 91a1f91440a974dfce4c0e1bedc2756d4f632972
Author: Colin Walters <walters verbum org>
Date:   Tue Jan 26 16:48:37 2016 -0500

    refs: Add a missing `goto out` for error handling
    
    If the `refs/remotes` directory doesn't exist, we'd trip an assertion.

 src/libostree/ostree-repo-refs.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/libostree/ostree-repo-refs.c b/src/libostree/ostree-repo-refs.c
index 6d3bd51..4fc415b 100644
--- a/src/libostree/ostree-repo-refs.c
+++ b/src/libostree/ostree-repo-refs.c
@@ -551,6 +551,8 @@ ostree_repo_list_refs (OstreeRepo       *self,
       remote_enumerator = g_file_enumerate_children (self->remote_heads_dir, OSTREE_GIO_FAST_QUERYINFO,
                                                      0,
                                                      cancellable, error);
+      if (!remote_enumerator)
+        goto out;
 
       while (TRUE)
         {