[Telemetry] Reduce misleading spam in unittest output.

tools/telemetry/telemetry/util/exception_formatter.py

Index: tools/telemetry/telemetry/util/exception_formatter.py
diff --git a/tools/telemetry/telemetry/util/exception_formatter.py b/tools/telemetry/telemetry/util/exception_formatter.py
index 4468b7f844efcda5ba79b9edd2479691bbe63fde..402461b5a2811f0c0f919884083af1aad5bb7170 100644
--- a/tools/telemetry/telemetry/util/exception_formatter.py
+++ b/tools/telemetry/telemetry/util/exception_formatter.py
@@ -9,10 +9,12 @@ import os
 import sys
 import traceback
 
+from telemetry.core import exceptions
 from telemetry.core import util
 
 
-def PrintFormattedException(exception_class=None, exception=None, tb=None):
+def PrintFormattedException(exception_class=None, exception=None, tb=None,
+                            msg=None):
   if not (bool(exception_class) == bool(exception) == bool(tb)):
     raise ValueError('Must specify all or none of '
                      'exception_class, exception, and tb')
@@ -20,6 +22,9 @@ def PrintFormattedException(exception_class=None, exception=None, tb=None):
   if not exception_class:
     exception_class, exception, tb = sys.exc_info()
 
+  if exception_class == exceptions.IntentionalException:
+    return
+
   def _GetFinalFrame(tb_level):
     while tb_level.tb_next:
       tb_level = tb_level.tb_next
@@ -29,6 +34,11 @@ def PrintFormattedException(exception_class=None, exception=None, tb=None):
   frame = _GetFinalFrame(tb)
   exception_list = traceback.format_exception_only(exception_class, exception)
   exception_string = '\n'.join(l.strip() for l in exception_list)
+
+  if msg:
+    print >> sys.stderr
+    print >> sys.stderr, msg
+
   _PrintFormattedTrace(processed_tb, frame, exception_string)