[1.6.x] Fixed #20829 -- Skip postgis metadata tables with introspection

Backport of 24088618 from master.

django/contrib/gis/db/backends/postgis/introspection.py

@@ -9,6 +9,14 @@ class PostGISIntrospection(DatabaseIntrospection):
     # introspection is actually performed.
     postgis_types_reverse = {}
 
+    ignored_tables = DatabaseIntrospection.ignored_tables + [
+        'geography_columns',
+        'geometry_columns',
+        'raster_columns',
+        'spatial_ref_sys',
+        'raster_overviews',
+    ]
+
     def get_postgis_types(self):
         """
         Returns a dictionary with keys that are the PostgreSQL object

django/db/backends/postgresql_psycopg2/introspection.py

@@ -25,7 +25,9 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
         1266: 'TimeField',
         1700: 'DecimalField',
     }
-        
+
+    ignored_tables = []
+
     def get_table_list(self, cursor):
         "Returns a list of table names in the current database."
         cursor.execute("""
@@ -35,7 +37,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             WHERE c.relkind IN ('r', 'v', '')
                 AND n.nspname NOT IN ('pg_catalog', 'pg_toast')
                 AND pg_catalog.pg_table_is_visible(c.oid)""")
-        return [row[0] for row in cursor.fetchall()]
+        return [row[0] for row in cursor.fetchall() if row[0] not in self.ignored_tables]
 
     def get_table_description(self, cursor, table_name):
         "Returns a description of the table, with the DB-API cursor.description interface."