[Bug] ISIN ignored in CSV import

Environment

Wealthfolio 3.7.0, 3.8.0 (WF); Windows 10 x64 in UK.

Steps to reproduce

Use a "Test1" dummy account, "Transactions" tracking mode, GBP currency.

CSV import this file, using the Default template:

"Date", "symbol", "isin", "quantity", "activityType", "unitPrice", "amount", "fee", "account", "currency"
"2019-06-19 08:51:00", "ATT.L", "GB00BNG2M159",  "1052", "Buy", "16.1478", "", "95.89", "Test1", "GBP"

What actually happens

I am asked to map the symbol "ATT.L".

What should actually happen

Given the ISIN and the currency (in the CSV and/or as the account's currency) are explicitly specified, the symbol does not need to be mapped: ISIN + currency uniquely identifies a product. WF should identify the product unambiguously.