number formatter adds prefix if format suffix is longer than format string

Steps to Reproduce

http://zkfiddle.org/sample/29g96nl/1-formatter-string-prefix
run fiddle

each intbox / doublebox uses a format with a suffix (for example, to show the units after a number)

Current Result

If the unit label is longer than the format and the format string ends with #0, the first Nth characters of the suffix are added as prefix, where N = suffix length - format string lenght

Expected Result

Prefixes shouldn't be added in this case

Debug Info

generated here:
https://github.com/zkoss/zk/blob/db507648f04ab391d471a61dec5fed7d3a6c3a3e/zk/src/archive/web/js/zk/fmt/numfmt.js#L297-L304

Root Cause

Workaround