Library Mod Reobf Issue

Here's my setup: I have my mod (Boxes) and my library (MLCore). Both are compiled with Jenkins and do just fine. I extract two jars from each: a standard one, and an unobfuscated dev one. I use the unobfuscated MLCore jar for adding to mcp/lib when compiling Boxes. However, things aren't reobfuscated if (in Boxes) I extend a class from MLCore that extends a class from Minecraft. e.g. I have a class tree that looks like this:

TileEntitySafe (in Boxes) -> TileEntitityConnectable (in MLCore) -> TileEntity

But, TileEntitySafe isn't obfuscated correctly. Fields don't obfuscate to field_xxxxx_x. Same with methods. It seems like there would have to be a way to correct this. Anybody have any ideas?