this is such a crude hack it is totally embarrassing....
the proper solution would probably be to move the `build_parser()`
function out of `Archiver` completely, but this is such an undertaking
that i doubt it is worth doing since we're looking at switching to
click anyways.
the main problem in moving build_parser() out is that it references
`self` all the time, so it *needs* an archiver context that it can
reuse. we could make the function static and pass self in there by
hand, but it seems like almost a worse hack... and besides, we would
need to load the archiver in order to do that, which would break usage
all over again...
9cbc868764