Use schema qualification while accessing the catalog objects.

refs #3976

web/pgadmin/utils/driver/psycopg2/connection.py

@@ -526,7 +526,7 @@ SELECT
     has_database_privilege(db.oid, 'CREATE') as cancreate, datlastsysoid,
     datistemplate
 FROM
-    pg_database db
+    pg_catalog.pg_database db
 WHERE db.datname = current_database()""")
 
         if status is None:

web/pgadmin/utils/driver/psycopg2/server_manager.py

@@ -211,11 +211,11 @@ class ServerManager(object):
                         status, res = conn.execute_dict("""
 SELECT
     db.oid as did, db.datname, db.datallowconn,
-    pg_encoding_to_char(db.encoding) AS serverencoding,
-    has_database_privilege(db.oid, 'CREATE') as cancreate, datlastsysoid,
-    datistemplate
+    pg_catalog.pg_encoding_to_char(db.encoding) AS serverencoding,
+    pg_catalog.has_database_privilege(db.oid, 'CREATE') as cancreate,
+    datlastsysoid, datistemplate
 FROM
-    pg_database db
+    pg_catalog.pg_database db
 WHERE db.oid = {0}""".format(did))
 
                         if status and len(res['rows']) > 0: