fix test-laplace-petsc3d

[dschwoerer]

fix for part of #1981

[dschwoerer]

openmpi seems to also include . in PATH, however mpich doesn't.

[ZedThree]

Might also be an idea to just remove the try ... except? It's probably more useful to have the actual output printed and not do the rest of the tests, especially on Travis

[johnomotani]

Might also be an idea to just remove the try ... except? It's probably more useful to have the actual output printed and not do the rest of the tests, especially on Travis

I agree. The try...except was useful for developing/debugging the solver, but now that the tests do all pass, and should continue to, it would be better to fail immediately if one of them fails.

[dschwoerer]

Updated.

In that case test-communications could also be updated to fail early and not print the errors at the end, without context

[johnomotani]

In that case test-communications could also be updated to fail early and not print the errors at the end, without context

Done in #1983.