[metapost] Command "show" on a non-empty "path" makes mpost(1) return with error code 1

[Akira Kakuto]

Hi Luigi,

> I have to see the pre-C version of metapost --- but we could decide to
> accept a different behavior as well.

I have confirmed that mpost 0.641 exits with 0 in both cases.
So it will be better to follow 0.641 in this case.

Thanks,
Akira