Merge pull request numenta#3119 from vitaly-krugl/remove-import-error-logging

Suppress optional dependency on matplotlib without logging

Author: vitaly-krugl

src/nupic/research/monitor_mixin/plot.py

@@ -23,18 +23,19 @@
 Plot class used in monitor mixin framework.
 """
 
-import logging
 import os
 
 try:
   # We import in here to avoid creating a matplotlib dependency in nupic.
   import matplotlib.pyplot as plt
   import matplotlib.cm as cm
 except ImportError:
-  # Suppress; we log it at debug level to avoid polluting the logs of apps
-  # and services that don't care about plotting
-  logging.debug("Cannot import matplotlib. Plot class will not work.",
-                exc_info=True)
+  # Suppress this optional dependency on matplotlib. NOTE we don't log this,
+  # because python logging implicitly adds the StreamHandler to root logger when
+  # calling `logging.debug`, etc., which may undermine an application's logging
+  # configuration.
+  plt = None
+  cm = None