Every day, I have QA, tech support, my boss, and other developers tell me something that is not actually true, or simply omits any of the relevant information necessary to fix the problem. This is something you live with on a daily basis in a technical job involving complex systems that not everyone understands the entirety of.
If you can't solve a problem with only some information, and some of it incorrect, then how are you supposed to be able to help?
You are looking at this like it is a single-variable problem. This "test" should be easily solvable by a candidate. It is also a very bad one if it involves lying to the candidate. These two factors are not mutually exclusive.
If you can't solve a problem with only some information, and some of it incorrect, then how are you supposed to be able to help?