[tests] Fix MathTest failures on Mac OS X
[tests] Fix MathTest failures on Mac OS X

due to timezone settings.

duncanmortimer/ledger,paulbdavis/ledger,paulbdavis/ledger,duncanmortimer/ledger,afh/ledger,paulbdavis/ledger,duncanmortimer/ledger,afh/ledger,ledger/ledger,ledger/ledger,ledger/ledger,duncanmortimer/ledger,afh/ledger,paulbdavis/ledger,ledger/ledger,afh/ledger,paulbdavis/ledger,duncanmortimer/ledger,paulbdavis/ledger,ledger/ledger,duncanmortimer/ledger,duncanmortimer/ledger,afh/ledger,paulbdavis/ledger