Arvados

8281-arv-mount-retry

I got this once, but haven't gotten it again.

======================================================================
ERROR: test_KeepLongBinaryRWTest (tests.test_keep_client.KeepTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/src/arvados/sdk/python/tests/test_keep_client.py", line 63, in test_KeepLongBinaryRWTest
    blob_locator = self.keep_client.put(blob_str)
  File "/usr/src/arvados/sdk/python/arvados/retry.py", line 153, in num_retries_setter
    return orig_func(self, *args, **kwargs)
  File "/usr/src/arvados/sdk/python/arvados/keep.py", line 1065, in put
    data_hash, copies, thread_limiter.done()), service_errors, label="service")
KeepWriteError: failed to write 84d90fc0d8175dd5dcfab04b999bc956 (wanted 2 copies but wrote 1): service http://localhost:35762/ responded with 422 HTTP/1.1 100 Continuet
  HTTP/1.1 422 status code 422

After 3 more tries it passes, so I'm not sure if it's related to the bugfix. Rest of it LGTM.