Try a best filter expression

Author: sgillies

pytest.ini

@@ -1,7 +1,7 @@
 [pytest]
 filterwarnings =
     error
-    ignore:.*Plugin file tracers (Cython.Coverage.Plugin) aren't supported with PyTracer
+    ignore:.*Plugin file tracers.*
     ignore:.*Sequential read of iterator was interrupted*:RuntimeWarning
     ignore:.*negative slices or start values other than zero may be slow*:RuntimeWarning
     ignore:.*negative step size may be slow*:RuntimeWarning