Hmm.  I see.  The problem is that our desire to quote conflicts with mailcap's attempts to quote.

I now agree with you that run-mailcap's approach is correct, but creating a temporary alias is out of scope for findmatch.  That would need to be done by findmatch's caller.

I think we should add a documentation note about the problem and the solution.  I don't see any reliable way to detect the problem and raise an error for the same reason that quoting doesn't work. (The aliasing can tolerate false positives; but, for backward compatibility reasons, an error detection function here cannot.)

It would be possible to add a helper for the aliasing to 3.6, but if someone wants to propose that they should open an new issue for the enhancement.

I'm