bug#26136: core-updates: address@hidden fails due to missing zlib

[Danny Milosavljevic]

Setting the environment variables

  CPPFLAGS="-I/gnu/store/y8c62fyb2x4g4qnl54pmlmid1fn8k3mx-zlib-1.2.8/include"
  LDFLAGS="-L/gnu/store/y8c62fyb2x4g4qnl54pmlmid1fn8k3mx-zlib-1.2.8/lib"

before running configure makes it work.

(I've also printed inc_dirs in setup.py without that - and zlib didn't appear)

So I guess the general question is how does Python set up inc_dirs ?

And is it normal that C_INCLUDE_PATH and LIBRARY_PATH doesn't contain zlib ? 
Apparently, since guix-master python2-minimal 2.7.12 doesn't contain it either 
-  and that one works...

So where would it get the other entries?