[gnome-settings-daemon/wip/claudio/CI] tests: Prevent SESSION_MANAGER environment variable to leak into test

[Benjamin Berg <bberg src gnome org>]

commit c0e4d0ba645276d8075c8c5e98f33058c98e32be
Author: Benjamin Berg <bberg redhat com>
Date:   Tue Feb 5 13:08:07 2019 +0100

    tests: Prevent SESSION_MANAGER environment variable to leak into test
    
    This appears to possible trigger crashes *outside* of the test
    environment.

 tests/gsdtestcase.py | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/tests/gsdtestcase.py b/tests/gsdtestcase.py
index 22a457a3..3d198cb0 100644
--- a/tests/gsdtestcase.py
+++ b/tests/gsdtestcase.py
@@ -61,6 +61,9 @@ class GSDTestCase(X11SessionTestCase):
         os.environ['LC_MESSAGES'] = 'C'
         klass.workdir = tempfile.mkdtemp(prefix='gsd-plugin-test')
 
+        # Prevent applications from accessing an outside session manager
+        os.environ['SESSION_MANAGER'] = ''
+
         # Signal to mutter and gnome-session that we are using X11
         os.environ['XDG_SESSION_TYPE'] = 'x11'