[FIX] account: Exchange test failing on Jun 6

The test `test_balanced_exchanges_gain_loss`
failed on Jun 6, because it created a specific rate
for today's date at midnight
(e.g. on Jun 6, 201x-06-06 00:00:00) for the test purpose,
but a rate is created in the demo data for Jun 6 midnight exactly:
`base.rateUSDbis`, making the test confused about which rate
to use.

We solve this by making the test use the rate `base.rateUSDbis`,
modifying the rate for its own need, instead of creating a new
rate.

0 files changed, 0 insertions, 0 deletions