This is (part of) the build output of a Ruby project, where dependencies are installed with Bundler:
[33mDon't run Bundler as root. Bundler can ask for sudo if it is needed, and installing your bundle as root will break this application for all non-root users on this machine.[0m
Note the [33m and [0m; these are ANSI-style color markers that can be parsed so the output is rendered in the actual color in the build output panel. Is that something Harbormaster should do?