/login 500s on invalid email addresses (SYN-502)

[matrixbot]

Hit /login with a bad email address and password. You get 500'd. Stack:

2015-10-20 10:52:29,158 - synapse.http.server - 108 - ERROR - POST-681228 - Failed handle request synapse.http.server._async_render on <synapse.rest.client.v1.ClientV1RestResource object at 0x51a6710>: <SynapseRe
quest at 0x7f239dc2e128 method=POST uri=/_matrix/client/api/v1/login? clientproto=HTTP/1.1 site=8080>
Traceback (most recent call last):
  File "synapse/http/server.py", line 87, in wrapped_request_handler
    yield d
  File "/mnt/disk/home/matrix/venv-synapse/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 1126, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/mnt/disk/home/matrix/venv-synapse/local/lib/python2.7/site-packages/twisted/python/failure.py", line 389, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "synapse/http/server.py", line 214, in _async_render
    callback_return = yield callback(request, *args)
  File "/mnt/disk/home/matrix/venv-synapse/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 1126, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/mnt/disk/home/matrix/venv-synapse/local/lib/python2.7/site-packages/twisted/python/failure.py", line 389, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "synapse/rest/client/v1/login.py", line 68, in on_POST
    result = yield self.do_password_login(login_submission)
  File "/mnt/disk/home/matrix/venv-synapse/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 1128, in _inlineCallbacks
    result = g.send(result)
  File "synapse/rest/client/v1/login.py", line 107, in do_password_login
    if not user_id.startswith('@&#8203;'):
AttributeError: 'NoneType' object has no attribute 'startswith'

Version: a8945d24d10e74c9011a2ba934799a201d19e12c

(Imported from https://matrix.org/jira/browse/SYN-502)

(Reported by @Kegsay)

[matrixbot]

Jira watchers: @Kegsay

[richvdh]

I reckon this has probably been fixed.