SigmaX/LightBDD — comment on commit be04364f119d2b06f7b09e23c2dbb20fd9c1abde
File:  line 0
By SigmaX:

In JCircuitTech, XOR and related functions evolved a lot faster before this bug was fixed.

I conjecture that it's because this bug corrupted the truth-tables of compositions, and turning an OR to an XOR, for instance, requires changing only one truth table row. Building a logic circuit for XOR is trickier, however.