Remove second declaration of temp Home variable `s_tempHome` on Unix systems

[alerickson]

PR Summary

This PR fixes a bug due to s_tempHome being redeclared (a scenario only applicable to Unix systems). After a value was set the variable would then fall out of scope and lose the value it should have been set to. This was causing a null pointer exception during install.

PR Context

Resolves #1527

PR Checklist

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