colorize is licensed under the GPL
Due to our dependency on the package_cloud gem, which in turn depends on colorize, we're violating the GPL by having Omnibus under Apache 2.0 right now.
Colorize is a GPLv2 gem, meaning anything depending on it must also be GPL licensed. It should probably be replaced by rainbow, as we did in gitlab-org/gitlab-ce!4425. I've tried getting the author of the gem to change the license, but he never responded.
The virality of the license is based on information provided by The GNU Project, as well as the Open Source Initiative, which both state that linking GPL libraries makes the program itself GPL.
See also: Our "Licensing" docs
cc: @stanhu @joedamato