net: Fix double-free using the Jamendo plugin
net: Fix double-free using the Jamendo plugin

The item in the queue is already freed when the source is removed,
through a destroy notify, so no need to do it twice.

Ensure we cancel the cancellable though, but do not unref it as we do
not own it.

https://bugzilla.gnome.org/show_bug.cgi?id=733232

grilofw/grilo,jasuarez/grilo,MathieuDuponchelle/grilo,GNOME/grilo,jasuarez/grilo,grilofw/grilo,jasuarez/grilo,MathieuDuponchelle/grilo,MathieuDuponchelle/grilo,grilofw/grilo,GNOME/grilo