[Telemetry] Don't display "Locals:" header if there are no locals to print.

tools/telemetry/telemetry/exception_formatter.py

Index: tools/telemetry/telemetry/exception_formatter.py
diff --git a/tools/telemetry/telemetry/exception_formatter.py b/tools/telemetry/telemetry/exception_formatter.py
index 553cca15023751c7d12481dc9377042e2bf667cd..8dafd44c2dae41923e6e446c2d92572b1b338323 100644
--- a/tools/telemetry/telemetry/exception_formatter.py
+++ b/tools/telemetry/telemetry/exception_formatter.py
@@ -48,7 +48,9 @@ def PrintFormattedException(exception_class, exception, tb):
   exception = ''.join([l[2:] if l[:2] == '  ' else l for l in
                        traceback.format_exception_only(exception_class,
                                                        exception)])
-  local_variables = _GetFinalFrame(tb).tb_frame.f_locals
+  local_variables = [(variable, value) for variable, value in
+                     _GetFinalFrame(tb).tb_frame.f_locals.iteritems()
+                     if variable != 'self']
 
   # Format the traceback.
   print >> sys.stderr
@@ -64,10 +66,8 @@ def PrintFormattedException(exception_class, exception, tb):
   if local_variables:
     print >> sys.stderr
     print >> sys.stderr, 'Locals:'
-    longest_variable = max([len(v) for v in local_variables.keys()])
-    for variable, value in sorted(local_variables.iteritems()):
-      if variable == 'self':
-        continue
+    longest_variable = max([len(v) for v, _ in local_variables])
+    for variable, value in sorted(local_variables):
       value = repr(value)
       possibly_truncated_value = _AbbreviateMiddle(value, ' ... ', 1024)
       truncation_indication = ''