The basic problem is that when I use marathon with bobs, I find that making bottled petroleum gas has steel beams as its ingredients, not petroleum and empty bottle, as I expect.
When I looked into it, I noticed that marathon (I have 1.1.5, the latest, I think) updates some bobs recipes, including "gas-canister" by doing a Recipe.select('gas-canister'). What I think is happening here, is that it is actually selecting anything which contains "gas-canister" i.e. "petroleum-gas-canister" and modifying that, instead.
Anyway, I'm not entirely sure who is responsible for this problem, but I guess the correct fix is to change Recipe.select to do exact matching on the full string only. I don't know who owns Recipe.select, though. Another solution would be to rename "petroleum-gas-canister" to just "petroleum-canister" as that should stop it from matching, if I have guessed the cause of the problem correctly.
ps. credit to redditer /u/CommutatorUmmocrotat for the subject
