|>>|| No. 2192
Even if they're labelled, never trust what's written on them unless you're bloody certain. It's all too common for dodgy electricians to spur off other mains circuits to make their life easier when installing a new light fitting, or to not bother properly relabelling after major work.
(Albeit in this case it sounds like OP has one of three lights still working so he could "test for dead" with that, at least. Personally I'd test with a probe just to be sure, and I'd certainly kill everything before sticking my hands anywhere near the fitting no matter how much of a rush I was in.)