spack load return code

[ax3l]

spack load nonExistingPackage

does not return a non-zero return code to bash.

Expected Result

A non-zero return code and a message that the package does not exist

Actual Result

Zero return code and no message.

Steps to reproduce the issue

$ spack bootstrap
# default tcl modules
$ spack load nonExistingPackage

Information on your system

Debian 9.2
Spack 8ae50ae8b

ccing @alalazo

[davydden]

see https://github.com/spack/spack/issues/2570

[healther]

I took a stab at this (feels like ages ago) and didn't come too far, but maybe it helps as a starting point #3827

[alalazo]

Duplicate of #2570