Update the valid_from date for the rate that is intended to start at the begining of the financial year.

It was the start of the financial year in BST, needed to convert it to UTC.
Small change to the logic to find the rates.

migrations/versions/0080_fix_rate_start_date.py

@@ -0,0 +1,24 @@
+"""empty message
+
+Revision ID: 0080_fix_rate_start_date
+Revises: 0079_update_rates
+Create Date: 2017-05-03 16:50:11.334116
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0080_fix_rate_start_date'
+down_revision = '0079_update_rates'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.get_bind()
+    op.execute("UPDATE RATES SET valid_from = '2017-03-31 23:00:00' WHERE valid_from = '2017-04-01 00:00:00'")
+
+
+def downgrade():
+    op.get_bind()
+    op.execute("UPDATE RATES SET valid_from = '2017-03-31 23:00:00' WHERE valid_from = '2017-04-01 00:00:00'")