Bad tracks count in playlist overview

Steps to reproduce

When clicking on Playlist the modal indicate a bad number of tracks:

Here there is 20 for playlist "My favorite Queen songs", while in the playlist page, the number of song is correct (10)

On the playlist overview the number should be 10.

Funkwhale version(s) affected: 0.17

Note: Each time I add 1 track the track counter is incremented by 2.

Edited Jan 03, 2019 by Floréal Toumikian