Add coverage

tools/telemetry/third_party/coverage/tests/backtest.py

+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt
+
+"""Add things to old Pythons so I can pretend they are newer, for tests."""
+
+# pylint: disable=redefined-builtin
+# (Redefining built-in blah)
+# The whole point of this file is to redefine built-ins, so shut up about it.
+
+
+# No more execfile in Py3
+try:
+    execfile = execfile
+except NameError:
+    def execfile(filename, globs):
+        """A Python 3 implementation of execfile."""
+        with open(filename) as fobj:
+            code = fobj.read()
+        exec(compile(code, filename, 'exec'), globs)