Underlines for shortcuts in menu bar at wrong location

Let's have a look at the Menus example:

This is how it looks in 4.7 (14de8cecfa). The underlines look like native Windows applications.

Now very same binary, but running on 4.8 (8485052e39):

The underlines seem connected to the letters. Thus, the menu bar looks non-native.

The same shows up in other applications, e. g. Qt Creator.