[CMake] Cannot create named generator when executing cmake through script (python)

[corey taylor]

I ran into a strange issue where on linux if I run cmake -G "Unix
Makefiles" via python.

eg. os.spawnvp(os.P_WAIT, program, args)

then cmake will error saying that it cannot create named generator
"Unix Makefiles".

However, if I copy and run the exact command in the terminal,
everything runs fine.

Any ideas?

corey