[gnome-builder] meson: fix build system type check when loading tests

[Christian Hergert <chergert src gnome org>]

commit d3ea00221bb75c3dd95d6a744adb722858551b82
Author: Christian Hergert <chergert redhat com>
Date:   Tue Jan 16 16:31:52 2018 -0800

    meson: fix build system type check when loading tests

 src/plugins/meson/gbp-meson-test-provider.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/plugins/meson/gbp-meson-test-provider.c b/src/plugins/meson/gbp-meson-test-provider.c
index e9b7dd136..139adcea9 100644
--- a/src/plugins/meson/gbp-meson-test-provider.c
+++ b/src/plugins/meson/gbp-meson-test-provider.c
@@ -280,7 +280,7 @@ gbp_meson_test_provider_reload (gpointer user_data)
    */
   context = ide_object_get_context (IDE_OBJECT (self));
   build_system = ide_context_get_build_system (context);
-  if (build_system == NULL)
+  if (!GBP_IS_MESON_BUILD_SYSTEM (build_system))
     IDE_RETURN (G_SOURCE_REMOVE);
 
   /*