Fix Fluid Conduit failure to extract

[codewarrior0]

A Fluid Conduit adjacent to multiple fluid containers, set to "Extract" on all of them, will stop extracting as soon as any of them become empty. A quick look at the source code suggests this line is the problem.

So, I'm giving you a completely untested change to a no-longer-maintained branch of your project just in case somebody finds it useful. Cheers!