Friendly relationship or not, the end user experience is that something that was working, no longer is, because it's not feature compatible. This is despite it being used to replace it under the same name. If it had been `runas` or anything else it'd be fine.

There's a strong principle in upstream Linux kernel about "You don't break userspace"[1], that I really wish more folks would get into their heads, but most especially a variant "You don't subtly break userspace".

If you're going to replace an existing binary, under the same name, you need to be like-for-like in commands, even if your guts are completely different. Very few people give a damn about how it's actually implemented, just does it do what they need it to do.

If you want to do things differently, do it under a different name and have it be an explicit break for an end user by not shipping with the original and let people choose to install it if they really don't want the new thing. Breaking things subtly is completely unacceptable.

[1] espoused really clearly, as part of an infamous rant https://lore.kernel.org/all/CA+55aFy98A+LJK4+GWMcbzaa1zsPBRo...

All the time wasted on navel-gazing could have been spent auditing and fixing the original projects' code.

Starting anew WILL introduce new bugs. This is a statistical certainty.

Most Rust rewrites are justified upon imaginary boogeymen. The complex security nightmares of 'cp' 'ls' and 'rm' were begging for a new design.