Hi Steven,

here is the first related PR: https://github.com/boostorg/build/pull/290
The next one (probably to Jamroot) will perhaps be a bit contentious, and require some back and forth. But the above is simple and a prerequisite to anything that follows, and thus it would be great to get that in quickly and independently.

Thanks,

-- 

      ...ich hab' noch einen Koffer in Berlin...