Make streams_menu tag more robust in the face of "request" missing

from context, this would normally be an error but it can happen if a
404 is returned
 - Legacy-Id: 6268

ietf/doc/templatetags/streams_menu.py

@@ -1,6 +1,7 @@
 from django import template
 from django.conf import settings
 from django.core.urlresolvers import reverse as urlreverse
+from django.contrib.auth.models import AnonymousUser
 
 from ietf.ietfauth.utils import has_role
 from ietf.group.models import Group
@@ -10,10 +11,10 @@ register = template.Library()
 
 @register.inclusion_tag('base/streams_menu.html', takes_context=True)
 def streams_menu(context):
-    user = context["request"].user
-
     editable_streams = []
 
+    user = context["request"].user if "request" in context else AnonymousUser()
+
     if user.is_authenticated():
         streams = StreamName.objects.exclude(slug="legacy")