The name of the directory inside could be either mnesia or mnesia-4.4.7 according to the Erlang manual.  Also the version in Elixir could be any string, including one that includes a dash. So this is a bit much but it was the most reliable thing I could think of.

Also just a note - I didn't include the version # in the "inner" folder here. I think we could do so, but I think it would have to be a little bit elaborate because :zip will only include actual path names, so we'd have to make a temp directory and copy the contents there before zipping.