add SYS_INTERNAL_ERR

Author: d-w-moore

irods/exception.py

@@ -666,6 +666,10 @@ class SYS_INVALID_INPUT_PARAM(SystemException):
     code = -130000
 
 
+class SYS_INTERNAL_ERR(SystemException):
+    code = -154000
+
+
 class SYS_BAD_INPUT(iRODSException):
     code = -158000