This is 5 years old and the Dockerfile no longer works.
It's fun!
This attitude is exactly why I rarely contribute to open source. You're not entitled to my work, just like I'm not entitled to yours. I'll do something myself if I want to.
If it's any consolation, the prevailing attitude in open source is that nobody is entitled to any work from others. We are not very good at calling people out on this bad attitude, so an occasional vocal exemplar can give the whole movement an unwelcoming outside impression. We should work on that.
I've been told this directly by project maintainers when filing bug reports (usually along the lines of "PRs welcome"), so it's not just that seeing this stuff on the internet puts me off from contributing in general. It's that people tend to respond directly with it whenever I come near their project.
I do still contribute to free software from time to time.