Since "6894072: always refresh keytab", we support "dynamic" keytabs which means a keytab file can change during the execution of a program, this even includes accepting a non-existing keytab at the beginning and read it when it appears at a later time.

On the other hand, the klist tool is used to list the current content of a static keytab file. When the file does not exist, we should warn the user. This behavior is also consistent with klist from other vendors.