Older versions have a nasty bug.
There's not many uqwk providers left as far as I can tell. Well until 2 or 3 weeks ago i'd suggest my shell home vex.net here in Toronto, Canada. Coincidentally also the home of the aging official yarn site. Except two or 3 weeks ago they switched OS's and ever since then i've been Uqwkless. I'm not very smart with C compilers.