QFile::canReadLine() always returns false

QIODevice::canReadLine() always returns false if the object is a QFile, even if the file contains linefeed characters.
E.g. the executable from the attached project always prints "Error: Cannot read line, but should be able to.".
This happens with the current git heads of both 4.7 and 4.8 (a96672bc77642e3e5a030fd9e78f700b47e11ccb and 262444086fe949441aebb6c6726ba13c97476191, respectively).