Environment: Ubuntu 20.04, uutils main branch (git commit 6a5f2aa), GNU coreutils v8.30

Steps to reproduce:

sort -C -c

What happens now: uutils sort behaves as if just -C was given (returning with exit status 0 if input was sorted or 1 if input was not sorted).

What I expected to happen: GNU sort terminates with an error message due to incompatible options:

sort: options '-cC' are incompatible

Notes: this is causing a failure in GNU test file tests/sort/sort.pl.