Definitely a modified pre-WW2 Polish pattern Vis holster. The uncertainty lies in the authenticity of the holster. Is it pre-war made, or an aged modern replica modified to deceive? I'd like to see better photo of the interior, but from the pics posted it does stands a good chance of being genuine.
Here are the pics for posterity. Please note for future reference that adding links without pics is not good as links die or pics get removed which leaves a useless post / thread for future reference.