I have never had my turn signals cancel from making any turns. If I "tap" the turn signal button at a traffic stop and I make the turn it still flashes for the same distance as when I use them for passing. And I have scraped the pegs on many a left/right turn that would definitely activate any angle sensor IF that disabled them.
So when I tap them at a traffic stop - I manually cancel them after I make the turn (but if I forget - they cancel themselves in less than a quarter mile).
The angle sensor is in the steering head. It senses when the forks are turned, in a slow speed turn, and then returned to center.