Hi Everyone,
I was redirected to this email list for help with b2. I am trying to build the docs for Boost.Optional, and in all honesty, I do not know if I have a problem with b2 o bjam or BoostBook or QuickBook or QuickDoc or xsltproc.

First, I am getting an error message:

error: mismatched versions of B2 engine and core
error: B2 engine (b2) is 4.4.1
error: B2 core (at /home/andrzej/Repos/boost/tools/build/src) is 4.9-git

This used to work until I recently made a `git pull --rebase` on Boost repo, which apparently put out of sync components "B2 engine" and "B2 core", whatever they may be. I have a `b2` in my /usr/bin -- I do not know where from, as I didnt know it comes with Fedora distributions (I thought it was Boost internal tool) -- of version 4.4, and I have another one in tools/build of version 4.9. I have been instructed to "rebuild the b2 engine executable", but I do not know how to do it, and which executable, as apparently I have got two. I would appreciate any detailed instructions on how to do it.