support: Make user search by email case-insensitive.

It's pretty troublesome to fail to find a user in our database because
they used a different capitalization when signing up.

analytics/tests/test_support_views.py

@@ -249,6 +249,12 @@ class TestSupportEndpoint(ZulipTestCase):
         check_hamlet_user_query_result(result)
         check_zulip_realm_query_result(result)
 
+        # Search should be case-insensitive:
+        assert self.example_email("hamlet") != self.example_email("hamlet").upper()
+        result = get_check_query_result(self.example_email("hamlet").upper(), 1)
+        check_hamlet_user_query_result(result)
+        check_zulip_realm_query_result(result)
+
         result = get_check_query_result(lear_user.email, 1)
         check_lear_user_query_result(result)
         check_lear_realm_query_result(result)

analytics/views/support.py

@@ -9,6 +9,7 @@ from urllib.parse import urlencode
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.core.validators import URLValidator
+from django.db.models import Q
 from django.http import HttpRequest, HttpResponse, HttpResponseRedirect
 from django.shortcuts import render
 from django.urls import reverse
@@ -289,7 +290,10 @@ def support(
     if query:
         key_words = get_invitee_emails_set(query)
 
-        users = set(UserProfile.objects.filter(delivery_email__in=key_words))
+        case_insensitive_users_q = Q()
+        for key_word in key_words:
+            case_insensitive_users_q |= Q(delivery_email__iexact=key_word)
+        users = set(UserProfile.objects.filter(case_insensitive_users_q))
         realms = set(Realm.objects.filter(string_id__in=key_words))
 
         for key_word in key_words: