message: Use Popen.communicate() instead of read() in stacktrace_handler_test.py.
  This avoids potential deadlock, see the warnings in
  I
  found that enabling the C API caused us to deadlock without this
  change.
diff: @@ -57,7 +57,8 @@ class StacktraceHandlerTest(test.TestCase):
  # Capture its output. capture both stdout and stderr and append them.
  # We are not worried about timing or order of messages in this test.
  - child_output = child_process.stdout.read() + child_process.stderr.read()
  + child_stdout, child_stderr = child_process.communicate()
  + child_output = child_stdout + child_stderr
  # Make sure the child process is dead before we proceed.
  child_process.wait()
  