Steps to reproduce the issue

$ spack install fenics%[email protected]~parmetis ^[email protected] ^[email protected]

Platform and user environment

Please report your OS here:

$ lsb_release -d
Description:	CentOS Linux release 7.6.1810 (Core)

Additional information

I tried activating spack activate py-ply the ply package before installing, but CMake is still unhappy...