Create default scope from python session only if needed
Create default scope from python session only if needed

Fixes test failures introduced with the commit
"Create default scope to read journal"
a9078767b8224a223f8942a1cb80d4544024387b

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