The zprint.vroom file has a dependency on zprint being installed, which isn't how other vroom files work, but strangely enough zprint.vroom "passes" after spitting out a bunch of errors if you try to run it without zprint installed. Example Travis run where it's doing that (since it was never set up to install zprint): https://travis-ci.org/google/vim-codefmt/jobs/654922984

Looks like the invocations that are failing are just verifying the command and the side-effects don't matter, so it would be fine to stub those out with a no-op system hijack.

@agriffis