Many state changes are not as reversible as one might think. Even chdir() can be non-reversible if the mountpoint has since changed. And if the locale has not

Many state changes are not as reversible as one might think. Even chdir() can be non-reversible if the mountpoint has since changed. And if the locale has not been set, and then a library sets it, AFAIK you can’t “unset” it, only set it to something else.