Feature request: parallel --halt-on-success, inverse of --halt-on-error

[Ævar Arnfjörð Bjarmason]

I just wrote this to speed up a single-threaded password cracker on an
8 core box:

    parallel --gnu --halt-on-error 2 'echo {} && (password-cracker
file && exit 1) || exit 0' ::: {1..8}

I.e. you want to exit as soon as some command returns success since
the password has been cracker.

Being able to do that as:

    parallel --gnu --halt-on-success 2 'echo {} && password-cracker
file' ::: {1..8}

Would be very neat.