[mutter/wip/nielsdg/meta-launcher-fix-error-free] meta-launcher: g_propagate_*_error takes ownership

[Niels De Graef <nielsdg src gnome org>]

commit b82fa2c6107f4c3e8249bd61c98f6a002a09b311
Author: Niels De Graef <niels degraef barco com>
Date:   Tue Feb 12 09:34:06 2019 +0100

    meta-launcher: g_propagate_*_error takes ownership
    
    This means we need to make sure we don't accidentally free the provided
    source GError (which automatically happens with `g_autoptr`), so use
    `g_steal_pointer()`.
    
    This fixes an issue where, when launched in a bubblewrap environment
    (such as the one provided by Buildstream), mutter would give the
    following warning message:
    
    ```
    mutter-WARNING **: 8:31:35:069: Can't initialize KMS backend: (null)
    ```
    
    ... which isn't that useful when trying to debug the actual issue.

 src/backends/native/meta-launcher.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/src/backends/native/meta-launcher.c b/src/backends/native/meta-launcher.c
index a43c1cc3d..93a1ca2f1 100644
--- a/src/backends/native/meta-launcher.c
+++ b/src/backends/native/meta-launcher.c
@@ -231,7 +231,9 @@ get_session_proxy (GCancellable *cancellable,
 
   if (!find_systemd_session (&session_id, &local_error))
     {
-      g_propagate_prefixed_error (error, local_error, "Could not get session ID: ");
+      g_propagate_prefixed_error (error,
+                                  g_steal_pointer (&local_error),
+                                  "Could not get session ID: ");
       return NULL;
     }
 
@@ -465,7 +467,9 @@ get_seat_id (GError **error)
 
   if (!find_systemd_session (&session_id, &local_error))
     {
-      g_propagate_prefixed_error (error, local_error, "Could not get session ID: ");
+      g_propagate_prefixed_error (error,
+                                  g_steal_pointer (&local_error),
+                                  "Could not get session ID: ");
       return NULL;
     }