The TagMap added in #269 is missing equals and hashCode implementations, making code that relies on NBTTagCompound comparisons not work at all.
Related: #270

I am clearly blind

While incomplete, NBTTagCompound#equals implementation asks for the tagMap's entrySet() to be equal, so that should be fine. Unless some mod is changing this behaviour.

NBTTagCompound#hashCode depends on tagMap's hashCode