Regression: Preferred subtitle language setting does not work anymore with MKV files

After upgrade from VLC 2.0.5 to 2.1.0 I recognized that the "Preferred subtitle language" setting is not respected anymore when using MKV files. I did not test it with other file types or DVDs etc.

I used to have "en" as my default subtitle language. The respective setting works still fine for audio tracks.

Expected result: The subtitle language I configured from Simple Preferences -> Subtitles -> Preferred subtitle language is used per default.

Actual result: The first subtitle language from the MKV file is used instead.