On the same bisect there's also this:
Traceback (most recent call last):
  File "/b/rr/tmpjQPE5m/rw/checkout/scripts/slave/recipe_modules/perf_dashboard/resources/post_json.py", line 38, in <module>
    sys.exit(main())
  File "/b/rr/tmpjQPE5m/rw/checkout/scripts/slave/recipe_modules/perf_dashboard/resources/post_json.py", line 27, in main
    response = requests.post(url, data=data)
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/api.py", line 88, in post
    return request('post', url, data=data, **kwargs)
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/api.py", line 44, in request
    return session.request(method=method, url=url, **kwargs)
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/sessions.py", line 338, in request
    resp = self.send(prep, **send_kwargs)
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/sessions.py", line 457, in send
    history = [resp for resp in gen] if allow_redirects else []
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/sessions.py", line 147, in resolve_redirects
    allow_redirects=False,
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/sessions.py", line 441, in send
    r = adapter.send(request, **kwargs)
  File "/b/rr/tmpjQPE5m/rw/checkout/third_party/requests_1_2_3/requests/adapters.py", line 327, in send
    raise ConnectionError(e)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='login.corp.google.com', port=443): Max retries exceeded with url: /request?s=chrome-perf.googleplex.com:443/uberproxy/&d=https://chrome-perf.googleplex.com/post_bisect_results%3Fupxsrf%3DADBfK3b09Uys-mSxupJn:1478899310812&maxAge=1200&authLevel=2000000&keyIds=MIG,ubk (Caused by <class 'httplib.BadStatusLine'>: '')
step returned non-zero exit code: 1
@@@STEP_LOG_LINE@json.output (invalid)@null@@@
@@@STEP_LOG_END@json.output (invalid)@@@
@@@STEP_FAILURE@@@

I have no idea what this might mean. At least later fyi jobs have succeeded.

I haven't seen any other instances of this; let's keep it open and see if it happens again when we run all bisects.

I did not see another instance of this over the weekend, lowering priority.

I haven't seen any other cases in a few days; closing as a transient error.