This is a actually not a bug, it’s a feature. 🙂
Okay, maybe not a feature, but a “working as designed”. ‘=’ is for integer comparisons, whereas ‘is’ is for string comparisons.
Now, the argument could be made that that is a stupid design, and I’d have a hard time arguing the point, but I’m not sure I want to work on it, as the playlist stuff will be different in next stable.