should tor-keymgr be using `FsMistrustErrorExt` ?

See the rustdocs for tor_persist::FsMistrustErrorExt. This is a trait which produces the right ErrorKind from a fs_mistrust::Error.

Probably, code in tor-keymgr that obtains kinds from mistrust errors should be using .keystore_error_kind() on the mistrust error. I think it may not currently be doing so.

Someone needs to go and look at the tor-keymgr code and check that the fs errorkinds are correct.

Prompted by this rather gnomic TODO HSS found in fs_mistrust_error_ext.rs:

    keystore, "a keystore"; // TODO HSS probably tor-keymgr should be using this

If this ticket seems to make no sense, then perhaps the TODO meant something else.

I'm going to tag this ticket MUST because I don't know really whether there is a serious bug here, but in any case it's probably not hard to sort out with the keymgr code in hand. Feel free to downgrade the ticket if that seems appropriate.