lxml fails to build and install on OS X 10.11

[Sorin Sbarnea]

"pip install --upgrade lxml" fails under OS X 10.11 and this should never happen,

This is an workround which works but the build script should do the trick itself instead of failing and having to "tune" the environment to make it work.

STATIC_DEPS=true LIBXML2_VERSION=2.9.2 pip install lxml

I found this workaround at http://louistiao.me/posts/installing-lxml-on-mac-osx-1011-inside-a-virtualenv-with-pip/ -- where you can find more details regarding the problems.

Please make it work by default, nobody want to waste time installing dependencies.

[scoder (scoder)]

Closing since we now have macOS wheels on PyPI.