Running rake spec:javascript from terminal does not find specs

[momolog]

When we go to /specs on our local server, we get

1 spec, 0 failures

but when we run RAILS_ENV=test bundle exec rake spec:javascript, it looks like there are no specs:

Running `"/usr/local/bin/phantomjs"  "/Users/aljoscha/.rvm/gems/ruby-2.2.2/gems/jasmine-rails-0.14.2/lib/jasmine_rails/../assets/javascripts/jasmine-runner.js" "file:///Users/aljoscha/rails/jovoto/tmp/jasmine/runner.html?spec="`
Running: file:///Users/aljoscha/rails/jovoto/tmp/jasmine/runner.html?spec=
Starting...

Finished
-----------------
0 specs, 0 failures in 0.004s.

ConsoleReporter finished

The weirdest part is, that opening the above mentioned file:///Users/aljoscha/rails/jovoto/tmp/jasmine/runner.html?spec= in a browser does run the spec successfully.

What could be the reason for this / how can we debug this?