Description:
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It would be nice to have the support of the Belarusian ruble currency format (ISO — BYN 933). Currency format is the same as that of the Russian ruble (RUR).

Test script:
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$fmt = new NumberFormatter('ru-RU', NumberFormatter::CURRENCY);

echo $fmt->formatCurrency(123.45, 'BYN');
echo PHP_EOL;
echo $fmt->formatCurrency(123.45, 'RUR');

Expected result:
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123,45 р.
123,45 р.

Actual result:
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123,45 BYN
123,45 р.