Reproduce:
$ npm install
$ ./node_modules/.bin/ganache-cli -p 9545 &
$ ./node_modules/.bin/ganache-cli -f 'http://localhost:9545'
In different terminal:
$ ./node_modules/.bin/truffle test
$ ./node_modules/.bin/truffle test --network ganache
Both tests pass
The first test passes, but the second run against the forked ganache instance fails