Only reproducible on 10.3, not on 10.2 (neither current nor somewhat older builds) and not on 10.4.
Slight modifications in the test case change the outcome. Here is the stack trace for the same test case, but without f10 column in both tables:
And if we also remove f9, we are getting an assertion failure instead:
We have several of these assertions filed, but I'm not sure either of them is quite the same case.