We guarded against the Unicode form being invalid and did not produce an
encoded form. But we did not guard against proper Punycode sequences
that decode to forms that had not passed the proper Nameprep stage. So
check for that and, if it fails, just keep the label in the form we
found it in (it's valid STD3 anyway).
[ChangeLog][QtCore][QUrl] Fixed a bug that caused certain domain names
that look like Internationalized Domain Names to become corrupt in
decoded forms of QUrl, notably toString() and toDisplayString().
Task-number: QTBUG-60364
Change-Id: Iadfecb6f28984634979dfffd14b833142cca8d0d
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
9e2c6899e0