lib/repo: Add return value to _ostree_repo_add_remote()

Return whether the remote already existed. This is an internal API, so
it’s not an API break. The return value will be useful in upcoming
commits for working out whether to later remove a remote again.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Closes: #875
Approved by: cgwalters

src/libostree/ostree-repo-private.h

@@ -351,7 +351,7 @@ gboolean
 _ostree_repo_update_mtime (OstreeRepo        *self,
                            GError           **error);
 
-void
+gboolean
 _ostree_repo_add_remote (OstreeRepo   *self,
                          OstreeRemote *remote);
 OstreeRemote *

src/libostree/ostree-repo.c

@@ -150,19 +150,23 @@ _ostree_repo_get_remote_inherited (OstreeRepo  *self,
   return g_steal_pointer (&remote);
 }
 
-void
+gboolean
 _ostree_repo_add_remote (OstreeRepo   *self,
                          OstreeRemote *remote)
 {
-  g_return_if_fail (self != NULL);
-  g_return_if_fail (remote != NULL);
-  g_return_if_fail (remote->name != NULL);
+  gboolean already_existed;
+
+  g_return_val_if_fail (self != NULL, FALSE);
+  g_return_val_if_fail (remote != NULL, FALSE);
+  g_return_val_if_fail (remote->name != NULL, FALSE);
 
   g_mutex_lock (&self->remotes_lock);
 
-  g_hash_table_replace (self->remotes, remote->name, ostree_remote_ref (remote));
+  already_existed = g_hash_table_replace (self->remotes, remote->name, ostree_remote_ref (remote));
 
   g_mutex_unlock (&self->remotes_lock);
+
+  return already_existed;
 }
 
 static gboolean