Difference in edge types is ignored by the matcher in limited circumstances

[hmillerbakewell]

I think this is in particular matching bare wires. I'll write a test in a moment to show what I mean, and here is a project that demonstrates it: doubling.zip

Open up the derivation "mixed," then the rule zip-zip2 will apply not just on doubled wires (as it should) but also on thin wires (where it shouldn't.)