uutils coreutils env Local Denial of Service via Improper Handling of Backslashes in Split-String Mode

A logic error in the env utility of uutils coreutils causes a failure to correctly parse command-line arguments when utilizing the -S (split-string) option. In GNU env, backslashes within single quotes are treated literally (with the exceptions of \\ and \'). However, the uutils implementation incorrectly attempts to validate these sequences, resulting in an "invalid sequence" error and an immediate process termination with an exit status of 125 when encountering valid but unrecognized sequences like \a or \x. This divergence from GNU behavior breaks compatibility for automated scripts and administrative workflows that rely on standard split-string semantics, leading to a local denial of service for those operations.