Where did audacious-plugins-dbg go?

There's a bug in audacious that the stack trace for which hits

#3 0x00007f1e81b963df in ()
    at /usr/lib/x86_64-linux-gnu/audacious/General/skins.so

...but looking at this there does not appear to be any file to determine what exactly this is. Presumably it used to be in audacious-plugins-dbg that used to be available as recently as xenial, but disappeared in debian upstream in jessie / https://packages.debian.org/jessie/audacious-plugins-dbg https://packages.ubuntu.com/en/trusty/devel/audacious-plugins-dbg
what happened to this package? Are the symbols supposed to just be in the audacious-plugins package by default now? Is it a bug that they aren't or is that a feature?