Rewrote the head-of-rotation review assignment loop to guarantee that it will terminate. This should fix the 'gateway timeout' issues we've seen lately, when review request volume in some review teams have been such that multiple assignments to the head of queue members have triggered the issue.

 - Legacy-Id: 14684

Author: levkowetz

ietf/group/views.py

@@ -1476,19 +1476,20 @@ def manage_review_requests(request, acronym, group_type=None, assignment_status=
             assignments_by_person = dict()
             for r in reqs_to_assign:
                 if r.form.cleaned_data["reviewer"]:
-                    assignments_by_person[r.form.cleaned_data["reviewer"].person] = r
+                    person = r.form.cleaned_data["reviewer"].person
+                    if not person in assignments_by_person:
+                        assignments_by_person[person] = []
+                    assignments_by_person[person].append(r)
 
             # Make sure the any assignments to the person at the head
             # of the rotation queue are processed first so that the queue
             # rotates before any more assignments are processed
             head_of_rotation = reviewer_rotation_list(group)[0]
             while head_of_rotation in assignments_by_person:
-                review_req = assignments_by_person[head_of_rotation]
-                assign_review_request_to_reviewer(request, review_req, review_req.form.cleaned_data["reviewer"],review_req.form.cleaned_data["add_skip"])
-                if review_req in reqs_to_assign:
-                    # XXX FIXME: It's not clear how we could end up here, but
-                    # it has happened.  See traceback email dated 14 Feb 2018
+                for review_req in assignments_by_person[head_of_rotation]:
+                    assign_review_request_to_reviewer(request, review_req, review_req.form.cleaned_data["reviewer"],review_req.form.cleaned_data["add_skip"])
                     reqs_to_assign.remove(review_req)
+                del assignments_by_person[head_of_rotation]
                 head_of_rotation = reviewer_rotation_list(group)[0]
 
             for review_req in reqs_to_assign: