[PATCHv8] nss_db: protect against empty mappings

[Carlos O'Donell]

On 7/12/19 11:13 PM, DJ Delorie wrote:
> 2. Any text other than the PASS/FAIL/etc lines should be assumed ignored
>     by any script that parses the output, or by developers who
>     auto-filter-out everything else because "it's never relevent".

Then mark them FAIL?

I'm trying to get to a point where a full `make` followed by `make check`
results in a functioning and correct regression test environment.

This whole point is moot though if we agree to a `make fastcheck` which
doesn't so the install, and a `make check` that always does the install.

-- 
Cheers,
Carlos.