Record sets with duplicate records cause server exception.

[benanhalt]

Discovered in the course of investigating #601.

#601 (comment)_

[benanhalt]

Accessing a record set with duplicates produces the following exception:

Internal Server Error: /api/specify/collectionobject/52356/
Traceback (most recent call last):
  File "/home/ben/src/specify7/ve/local/lib/python2.7/site-packages/django/core/handlers/exception.py", line 39, in inner
    response = get_response(request)
  File "/home/ben/src/specify7/ve/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 249, in _legacy_get_response
    response = self._get_response(request)
  File "/home/ben/src/specify7/ve/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/ben/src/specify7/ve/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/ben/src/specify7/specifyweb/specify/views.py", line 22, in wrapped
    return view(request, *args, **kwargs)
  File "/home/ben/src/specify7/ve/local/lib/python2.7/site-packages/django/views/decorators/cache.py", line 43, in _cache_controlled
    response = viewfunc(request, *args, **kw)
  File "/home/ben/src/specify7/specifyweb/specify/views.py", line 30, in wrapped
    return view(request, *args, **kwargs)
  File "/home/ben/src/specify7/specifyweb/specify/views.py", line 44, in view
    return dispatch_func(request, *args, **kwargs)
  File "/home/ben/src/specify7/specifyweb/specify/api.py", line 95, in resource_dispatch
    data = get_resource(model, id, request.GET.get('recordsetid', None))
  File "/home/ben/src/specify7/specifyweb/specify/api.py", line 204, in get_resource
    data['recordset_info'] = get_recordset_info(obj, recordsetid)
  File "/home/ben/src/specify7/specifyweb/specify/api.py", line 218, in get_recordset_info
    rsi = rsis.get(recordid=obj.id)
  File "/home/ben/src/specify7/ve/local/lib/python2.7/site-packages/django/db/models/query.py", line 389, in get
    (self.model._meta.object_name, num)
MultipleObjectsReturned: get() returned more than one Recordsetitem -- it returned 5!
[18/Feb/2020 15:06:58] [ERROR] [django.server:131] "GET /api/specify/collectionobject/52356/?recordsetid=21 HTTP/1.1" 500 7175

[specifysoftware]

This issue has been mentioned on Specify Community Forum. There might be relevant details there:

https://discourse.specifysoftware.org/t/workbench-data-set-validation-error-more-than-one-picklist-in-specify-7/1080/3