title: How to install Modular Boost?
body: <p>Because I need to test some experimental features of Boost, I would like to install Boost from the Modular Boost repository. </p>
  
  <p>I followed the instructions on <a href="https://svn.boost.org/trac/boost/wiki/TryModBoost" rel="noreferrer">https://svn.boost.org/trac/boost/wiki/TryModBoost</a> and the b2 command failed:</p>
  
  <pre><code>./b2 headers
  /home/wichtounet/src/modular-boost/tools/build/src/build/feature.jam:493: in feature.validate-value-string from module feature
  error: "none" is not a known value of feature &lt;optimization&gt;
  error: legal values: "off" "speed" "space"
  /home/wichtounet/src/modular-boost/tools/build/src/build/property.jam:273: in validate1 from module property
  /home/wichtounet/src/modular-boost/tools/build/src/build/property.jam:299: in property.validate from module property
  /home/wichtounet/src/modular-boost/tools/build/src/tools/builtin.jam:377: in variant from module builtin
  /usr/share/boost-build/site-config.jam:9: in modules.load from module site-config
  /home/wichtounet/src/modular-boost/tools/build/src/build-system.jam:249: in load-config from module build-system
  /home/wichtounet/src/modular-boost/tools/build/src/build-system.jam:351: in load-configuration-files from module build-system
  /home/wichtounet/src/modular-boost/tools/build/src/build-system.jam:524: in load from module build-system
  /home/wichtounet/src/modular-boost/tools/build/src/kernel/modules.jam:289: in import from module modules
  /home/wichtounet/src/modular-boost/tools/build/src/kernel/bootstrap.jam:139: in boost-build from module
  /home/wichtounet/src/modular-boost/boost-build.jam:17: in module scope from module
  </code></pre>
  
  <p>I tried adding optimization=speed on the command line, but it didn't changed a thing. I tried the master and develop branches. I tried with clang and gcc toolset. </p>
  
  <p>Does someone has an idea how to install Modular Boost ? </p>
  
  <p>Is there some configuration that is necessary (and where) ? Or is there another procedure to follow ?</p>
  
  <p>EDIT: It seems that it comes from the /usr/share/boost-build/site-config.jam file that is probably installed by Gentoo. I need to be able to tell b2 to ignore this file. </p>