I have been trying to build (pip install) mercurial - for ages. I kept running into this message:

    "/opt/include/python2.7/pyport.h", line 887.2: 1506-205 (S) #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)."

And - finally, I figured out what I -- WAS -- doing wrong.

I package python as 64-bit, but when I just install python and then try pip install mercurial the message shows up.

The problem goes away when I first export OBJECT_MODE

export OBJECT_MODE=64

The little enhancement would be to change the hint from

... (bad gcc/glibc config?) to something that hints at
machine size, e.g., (bad default bit-size for compiler?)