Daylight sensor emits power in the nether even though there's no day or night there

the daylight sensor emits power in the nether even though there's no day or night there.

what I expected to happen was: it wouldn't work at all, or flickr quickly between on and off, like the compass or clock

what actually happened was: it stayed on.

steps to reproduce:
1.place down daylight detector in nether
2. attach redstone dust