Stop reading ~/.torrc during stem's test_hush_argument
In #30102 (moved), we put random data in ~/.torrc, which breaks stem's test_hush_argument test.
======================================================================
FAIL: test_hush_argument
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/travis/build/torproject/tor/stem/stem/util/test_tools.py", line 152, in <lambda>
self.method = lambda test: self.result(test) # method that can be mixed into TestCases
File "/home/travis/build/torproject/tor/stem/stem/util/test_tools.py", line 225, in result
test.fail(self._result.msg)
AssertionError: Expected '[warn] Failed to parse/validate config: Unknown option 'invalid_argument'. Failing.' to be within 'Aug 01 20:10:11.551 [warn] Failed to parse/validate config: Unknown option '����QT��
~��V���vLҶ�
���\��ޠ@qw�F��0v��$5�EJ��hܱd�FӺTm��Oo'. Failing.
Aug 01 20:10:11.562 [err] Reading config failed--see warnings above.
'
----------------------------------------------------------------------