Cannot specify subdir with circle

[calebshay]

I have several GitHub repos with a general layout of:

reponame
  |_server
  |_client

server and client are two separate elixir projects. As part of my circle build/test, I run mix coveralls.circle --parallel within each of these subdirectories, and once they are both complete, I submit the completion via curl. However, because they are in subdirectories, coveralls.io gets the paths all wrong for the files. Why can't I use the --subdir flag with coveralls.circle to take care of that issue?