Windows app fails WACK test due to missing UTF BOM

After building app for store and running WACK it fails with the following error:

File encoding test

FAILED
UTF-8 file encoding
Error Found: The UTF-8 file encoding test detected the following errors:
File C:\Program Files\WindowsApps\57757VladimirKotikov.CordovaTest123_1.1.0.0_x64__gpj6r6j8n5kcg\www\cordova_plugins.js is not properly UTF-8 encoded. Re-save the file as UTF-8 (including Byte Order Mark).
Impact if not fixed: HTML, CSS, and JavaScript files must be encoded in UTF-8 form with a corresponding byte-order mark (BOM) in order to benefit from bytecode caching and to avoid other runtime error conditions.
How to fix: Open the affected file, and select "Save As..." option from the File menu in Visual Studio. Select the drop-down control next to the Save button and select "Save with Encoding..." option. From the Advanced save options dialog, choose the "Unicode (UTF-8 with signature)" option and click the OK button.