This patch adds support for the -u flag for the env command. The -u flag allows users to explicitly unset an environment variable for a particular command. This is useful for OpenMP which heavily relies on environment variables to determine the library's behavior in certain situations. So being able to unset a potentially polluted environment is important.
env -u FOO -u BAR GOO=16 CAR=5
This removes both FOO and BAR from the environment while setting GOO=16 and HAR=5.