Always copy generated `spack.yaml`

[white238]

I've ran into cases where the spack.yaml is generated but wasn't copied due to failures. We should try to always do the copying.

uberenv/uberenv.py

Lines 933 to 934 in 991a9ce

	print("[copying spack yaml file to {0}]".format(copied_spack_yaml))
	sexe("cp {0} {1}".format(generated_spack_yaml, copied_spack_yaml))