From my pull request:
We have several scripts we use during application development that monitor long running processes with ruby-progressbar. We also have these scripts running in automated environments (such as CI), and the output in these situations is very noisy. We could alter the scripts, but I think it would be nicer if this library could gracefully handle these situations.
This patch adds a baseline behavior in non-tty environments so that things like log files aren't filled with every frame of the progress bar animation.
This was merged into the master branch, so one can pick up the change by using a
git source in her