Modify server_track to handle being called without a request.

[brianhw]

@rocha @mulby Here's a more minimalistic fix for AN-361. I'm splitting off the changes to add tracking context from a command into a separate PR, since that part is not required to be able to run create_user, and seems to engender more discussion.

[mulby]

why not simply: agent = request.META.get('HTTP_USER_AGENT', '')?

I tend to try to avoid bare except clauses if at all possible.

Maybe something like:

def get_request_header(request, header_name):
    if request is None or not hasattr(request, 'META') or header_name not in request.META:
        return ''
    else:
        return request.META[header_name]

event = {
    "ip": get_request_header(request, 'REMOTE_ADDR'),
    "host": get_request_header(request, 'SERVER_NAME'),
}

[brianhw]

Updated based on feedback from @mulby. (I had been too timid about request.META before, fearing that it was a QueryDict like POST and GET and might generate other errors. But META is just a dict, so we shouldn't need to use try/except to access META parameters.)

[rocha]

LGTM 🚀