[gnome-builder] flatpak: don't allow 'flatpak build' to spew information

[Christian Hergert <chergert src gnome org>]

commit 30201ce80742d81c17d2a4c9dc527841ebf7344c
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jan 7 13:21:47 2019 -0800

    flatpak: don't allow 'flatpak build' to spew information
    
    This can mess up communication with things like GDB.

 src/plugins/flatpak/gbp-flatpak-runner.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/src/plugins/flatpak/gbp-flatpak-runner.c b/src/plugins/flatpak/gbp-flatpak-runner.c
index dc2721704..f13f8c84b 100644
--- a/src/plugins/flatpak/gbp-flatpak-runner.c
+++ b/src/plugins/flatpak/gbp-flatpak-runner.c
@@ -133,6 +133,11 @@ gbp_flatpak_runner_fixup_launcher (IdeRunner             *runner,
         }
     }
 
+  /* Disable G_MESSAGES_DEBUG as it could cause 'flatpak build' to spew info
+   * and mess up systems that need a clean stdin/stdout/stderr.
+   */
+  ide_subprocess_launcher_setenv (launcher, "G_MESSAGES_DEBUG", NULL, TRUE);
+
   ide_subprocess_launcher_insert_argv (launcher, i++, self->build_path);
 }