title: numpy dependency in setup.py script used by bitbake
body: <p>We have a setup.py file for one of our Python modules. In setup.py we are actually using the numpy module to do some setup. The module itself also utilizes numpy.</p>
  
  <p>The setup.py works fine on our host machines.</p>
  
  <p>However, when we run the following bitbake recipe for our embedded platform, the build fails as it cannot find numpy. I checked and I cannot find what the PYTHONPATH variable is set to. Running bitbake -e | grep ^PYTHONPATH= returns nothing; so perhaps this is the problem?</p>
  
  <p>It may be that we are going about this wrong as well. Any insight into why its not working or advice on how to accomplish using bitbake with our setup.py would be greatly appreciated. </p>
  
  <p>Our recipe. I tried to use the matplotlib recipe as a baseline as I know that matplotlib has a numpy dependency. </p>
  
  <pre><code>DESCRIPTION = "our-pythonlib" 
  AUTHOR = "Author"
  MAINTAINER = "${AUTHOR}"
  SECTION = "company-apps" 
  LICENSE = "CLOSED"
  
  S="${THISDIR}/our-pythonlib"
  
  inherit distutils 
  
  
  # depend on following packages to work:
  RDEPENDS_${PN} += " \
      python-numpy \
      python-ctypes \
      python-json \   
      "
  
  EXTRA_OECONF = "--disable-docs --with-python-includes=${STAGING_INCDIR}/../"
  
  inherit distutils
  
  do_compile_prepend() {
      BUILD_SYS=${BUILD_SYS} HOST_SYS=${HOST_SYS} \
      ${STAGING_BINDIR_NATIVE}/python setup.py build ${DISTUTILS_BUILD_ARGS} || \
      true
  }
  
  # need to export these variables for python-config to work
  export PYTHONPATH
  export BUILD_SYS
  export HOST_SYS
  export STAGING_INCDIR
  </code></pre>