Buildcraft version: 7.99.12
Forge version: 14.23.1.2559
Link to crashreport or log (on pastebin or gist, please don't put the entire log here) : N/A
Singleplayer/multiplayer: Singleplayer

Additional information: The Slimeball to Pipe Sealant recipe isn't gate behind the config option as in previous BC 7.1.x versions.

Previous 7.1.x Config:
# Should I enable an alternate Waterproof recipe, based on slimeballs?
B:slimeballWaterproofRecipe=false

This config line does not exist, thus the recipe is automatically enabled.

The longer this recipe stays; the more people will get used to it, the more complaints you will get when it is gated back behind the config :P

Where is this class located? buildcraft.core.client.ConficGuiFactoryBC

That seems to be a dependency for loading that configuration option.

Do you mean ConfigGuiFactory.java?

Either way the config option itself should probably be in BCTransportConfig.java as that's where all the other config options are for the transport module.

I'm talking about this line in BuildCraftCore.java#L78

Looks like a misspelling from way back:
4c6b9be

Regardless, if it belongs in a different file I'll look into it.

Oh right sorry, nothing in src_old_license is built as it's code from before the rewrite. So most of the source should be in the "common" folder instead.