Environment: Ubuntu 24.04, uutils main branch (git commit 3971bb3), GNU coreutils v9.6.38-2b088-modified

Steps to reproduce:

expr "a^b" : "a^b"

What happens now: uutils expr outputs 0 and terminates with exit status 1.

What I expected to happen: GNU expr outputs 3 and terminates with exit status 0.

Notes: this is causing a failure in GNU test file tests/expr/expr.pl (in test case bre10).