diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -1408,8 +1408,8 @@
         session = str(uuid.uuid4())
         if PYTHON3:
             session = session.encode('ascii')
-        hgcatapult = os.getenv('HGTESTCATAPULTSERVERPIPE') or \
-            os.getenv('HGCATAPULTSERVERPIPE')
+        hgcatapult = (os.getenv('HGTESTCATAPULTSERVERPIPE') or
+                      os.getenv('HGCATAPULTSERVERPIPE'))
         def toggletrace(cmd=None):
             if not hgcatapult or hgcatapult == os.devnull:
                 return