Partial revert of 81768fc (#6398) (#6430)

This queryset introduced a bug where a from_url of 5 characters would
produce and exception.

readthedocs/redirects/querysets.py

@@ -1,8 +1,6 @@
 """Queryset for the redirects app."""
 
 from django.db import models
-from django.db.models import Value, CharField, IntegerField, Q, F, ExpressionWrapper
-from django.db.models.functions import Substr, Length
 
 from readthedocs.core.utils.extend import SettingsOverrideObject
 
@@ -27,79 +25,7 @@ def api(self, user=None, detail=True):
         return queryset
 
     def get_redirect_path_with_status(self, path, full_path=None, language=None, version_slug=None):
-        # add extra fields with the ``path`` and ``full_path`` to perform a
-        # filter at db level instead with Python
-        queryset = self.annotate(
-            path=Value(
-                path,
-                output_field=CharField(),
-            ),
-            full_path=Value(
-                full_path,
-                output_field=CharField(),
-            ),
-
-            from_url_length=ExpressionWrapper(
-                Length('from_url'),
-                output_field=IntegerField(),
-            ),
-
-            # 1-indexed
-            from_url_without_rest=Substr(
-                'from_url',
-                1,
-                F('from_url_length') - 5,  # Strip "$rest"
-                output_field=CharField(),
-            ),
-
-            # 1-indexed
-            full_path_without_rest=Substr(
-                'full_path',
-                1,
-                F('from_url_length') - 5,  # Strip "$rest"
-                output_field=CharField(),
-            ),
-        )
-        prefix = Q(
-            redirect_type='prefix',
-            path__startswith=F('from_url'),
-        )
-        page = Q(
-            redirect_type='page',
-            path__iexact=F('from_url'),
-        )
-        exact = (
-            Q(
-                redirect_type='exact',
-                from_url__endswith='$rest',
-                # This works around a bug in Django doing a substr and an endswith,
-                # so instead we do 2 substrs and an exact
-                # https://code.djangoproject.com/ticket/29155
-                full_path_without_rest=F('from_url_without_rest'),
-            ) | Q(
-                redirect_type='exact',
-                full_path__iexact=F('from_url'),
-            )
-        )
-        sphinx_html = (
-            Q(
-                redirect_type='sphinx_html',
-                path__endswith='/',
-            ) | Q(
-                redirect_type='sphinx_html',
-                path__endswith='/index.html',
-            )
-        )
-        sphinx_htmldir = Q(
-            redirect_type='sphinx_htmldir',
-            path__endswith='.html',
-        )
-
-        # There should be one and only one redirect returned by this query. I
-        # can't think in a case where there can be more at this point. I'm
-        # leaving the loop just in case for now
-        queryset = queryset.filter(prefix | page | exact | sphinx_html | sphinx_htmldir)
-        for redirect in queryset.select_related('project'):
+        for redirect in self.select_related('project'):
             new_path = redirect.get_redirect_path(
                 path=path,
                 language=language,