Minimize filename during TestInput test

[d-torrance]

This should fix #3419 (comment)

[mahrud]

I probably should have checked this more thoroughly. It didn't address the issue:

 -- i7 : assert Equation(toSequence locate pkgtest, (testpkg, 3, 5, 3, 32, 3, 5))
 -- stdio:10:6:(3): error: assertion failed:
 -- (../../M2-94666-0/0.m2, 3, 5, 3, 32, 3, 5) == (/private/tmp/M2-94666-0/0.m2, 3, 5, 3, 32, 3, 5) is false
 -- 
stdio:1:5:(3): error: test(s) #333 of package Core failed.

[d-torrance]

Oops, I just fixed one of the assert statements! There are a few. Let me try again...