Found on bunya make fails (unless nlopt disabled) due to mpi.rank

[TravisMitchell]

I think this was just an outdated reference with mpi.rank - switched to mpi_rank as per other handlers and compile goes ahead.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (93bf342) 36.69% compared to head (948cd34) 36.69%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #487 +/- ## ======================================== Coverage 36.69% 36.69% ======================================== Files 183 183 Lines 8380 8380 ======================================== Hits 3075 3075 Misses 5305 5305 ``` | [Flag](https://app.codecov.io/gh/CFD-GO/TCLB/pull/487/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CFD-GO) | Coverage Δ | | |---|---|---| | [d3q27_PSM_NEBB](https://app.codecov.io/gh/CFD-GO/TCLB/pull/487/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CFD-GO) | `32.16% <ø> (ø)` | | | [d3q27_pf_velocity](https://app.codecov.io/gh/CFD-GO/TCLB/pull/487/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CFD-GO) | `27.34% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CFD-GO#carryforward-flags-in-the-pull-request-comment) to find out more.

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[llaniewski]

@TravisMitchell This has a bit messy commit history, so I'll "squash" it. After that you can replace your develop branch with this.