[gdm/gnome-3-28] libgdm: Don't unref a connection that's in use

[Iain Lane <iainl src gnome org>]

commit 68910f303a571dbe8ee4df57018c27a50b26aa7e
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed May 9 15:43:27 2018 +0100

    libgdm: Don't unref a connection that's in use
    
    If an async task tries to reuse an open connection,
    it erroneously explicitly unrefs it. That is incorrect,
    because there are weak references in use to handle
    disposing the connection when its no longer in use.
    
    This commit makes sure the local connection object
    in open_connection is nullified so the connection
    doesn't get autofree'd.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=795940
    (cherry picked from commit 4654042d22c71da599d60a7e2f0570acf3d4a166)

 libgdm/gdm-client.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/libgdm/gdm-client.c b/libgdm/gdm-client.c
index bcae8ba..c017bf8 100644
--- a/libgdm/gdm-client.c
+++ b/libgdm/gdm-client.c
@@ -583,6 +583,8 @@ gdm_client_open_connection_finish (GdmClient      *client,
 
         if (client->priv->connection == NULL) {
                 client->priv->connection = g_steal_pointer (&connection);
+        } else if (client->priv->connection == connection) {
+                connection = NULL;
         }
 
         finish_pending_opens (client, NULL);