Sbt 0.13.15 hangs

I’m trying out sbt 0.13.15. In a build step where sbt update is invoked, sbt drops into its interactive shell prompt. This should only happen if circleci is sending a newline into sbt’s stdin. Is that happening? If so, is there a way to suppress that?

It turns out this can be fixed by changing all the invocations of sbt e.g. sbt test to sbt test < /dev/null