A regression is the kernel not giving the same result with the same user space
Mercurial, made by another (in my opinion) much more well-spoken kernel hacker, is what really introduced me to the concept that you do not break interface for downstream users, no matter how wrongly you may think they are using the interface.It’s an attitude that is difficult to convey because software developers always want to have the freedom to “improve” their own software, even at the possible cost of breaking something for some users (and worse, even telling users that they shouldn’t have been doing that in the first place).I keep going back to this blog post which I wish more people agreed with (Steve Losh is another person influenced by Mercurial):http://stevelosh.com/blog/2012/04/volatile-software/