JustCoder

...
def extension(self, extension, option, output):
    if (extension == self.ChooseMultipleFilesExtension):
        if self.overrideUpload is None:
            return super(WebPage, self).extension(self, extension, option, output)
        file_upl = self.overrideUpload
        self.overrideUpload = None
        output.fileNames = QStringList([file_upl])
        return True
    return False
...