[REG 4->5] URL in QFileOpenEvent on OS X is getting a "file" scheme

In Qt 5, a URL beginning with "<scheme>://" as typed into a web browser is stripped of its second slash, becoming "<scheme>:/", by the time it is delivered in association with a QFileOpenEvent to the QApplication registered as the handler for the protocol.

To reproduce, start with an example that inherits QApplication, e.g., qtbase/examples/widgets/widgets/tablet. Insert the following within the body of TabletApplication::event(Qevent *event) in tabletapplication.cpp:

     if (event->type() == QEvent::FileOpen)
     { 
         qDebug() << "fileOpen event:  url is" << static_cast<QFileOpenEvent *>(event)->url();
         qDebug() << "fileOpen event: file is" << static_cast<QFileOpenEvent *>(event)->file();
     }

Build the project.

Now insert the following within tablet.app/Contents/Info.plist to register tablet.app as the handler for the custom "tablet-example-qt5" protocol:

 	<key>CFBundleURLTypes</key>
 	<array>
 		<dict>
 			<key>CFBundleURLName</key>
 			<string>Tablet Example</string>
 			<key>CFBundleURLSchemes</key>
 			<array>
 				<string>tablet-example-qt5</string>
 			</array>
 		</dict>
 	</array>

If necessary, copy tablet.app to a new location (e.g., ~/Desktop) to force an update of the Launch Services database and force the registration to take effect immediately.

Within a web browser (e.g., Safari), enter URL

tablet-example-qt5://testurl

The tablet application is launched and prints console messages:

fileOpen event:  url is  QUrl( "file:tablet-example-qt5:/testurl" ) 
fileOpen event: file is "tablet-example-qt5:/testurl"

Note that the second slash from the "://" in the original URL has been stripped. (In fact, no matter how many slashes you type following the colon, all slashes beyond the first are stripped.)

This is a regression from Qt 4. Following a similar procedure at Qt 4.8.6 yields console messages:

fileOpen event:  url is  QUrl( "tablet-example-qt4://testurl" )
fileOpen event: file is ""

Related: QTBUG-34801: Qt5 Mac application cannot handle custom url scheme