Using --push-results and pry breakpoints doesn't show any output

I've recently discovered the --push-results option, which is great.` However, pry breakpoints don't work when using this option:

before_session hook failed: Errno::ENOTTY: Inappropriate ioctl for device
~/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/pry-0.9.12.2/lib/pry/terminal.rb:45:in `winsize'
(see _pry_.hooks.errors to debug)

And then the console doesn't give any output after typing ruby methods there.

Breakpoints work perfectly fine when running the server without the --push-results option.

I forgot to add I'm using spin 0.7.0. With spin 0.6.2, the behavior is different: the pry console opens in the shell where the server is running, but the output from the pry console is printed in the shell pushing the tests.