title: Django DisallowedModelAdminLookup for lookup in Admin list_filter
body: <p>I have a <code>Member</code> model and an <code>Organization</code> model, joined via a <code>PrincipleMembership</code> model. <code>PrincipleMembership</code> has <code>ForeignKey</code> fields for <code>Member</code> and <code>Organization</code>.</p>
  
  <p>I create <code>MemberAdmin</code> with the line <code>list_filter = ['principlemembership__organization__type', ]</code>, the filter renders perfectly, but clicking on it produces the <code>DisallowedModelAdminLookup</code> exception.</p>
  
  <p>I can fix it by overriding <code>ModelAdmin.Lookup_allowed</code> to permit <code>principlemembership__organization__type__exact</code>, but is this a bug in Django? I'm on Python 3.5.3 and Django 1.10.</p>
  
  <p>I have tried adding filters on <code>organization.type</code> to <code>OrganizationAdmin</code> and <code>PrincipleMembershipAdmin</code>, both of which work. I do not use a many to many join as I have other data on <code>PrincipleMembership</code>, such as <code>From</code> and <code>To</code> dates. I have tried making the filter explicitly a <code>admin.ChoicesFieldListFilter</code>. I have tried removing everything else from <code>MemberAdmin</code> except <code>list_filter = ['principlemembership__organization__type', ]</code>. I have tried a filter on a simple Char field on <code>Organization</code> and get the same error.</p>