GHC 8.0.2 introduced a bugfix involving GeneralizedNewtypeDeriving in
96d45145. This made typechecking of
GND-produced code a bit stricter, and an unfortunate side effect of this was
that there were a couple of corner-case programs that stopped compiling
when transitioning from GHC 8.0.1 to 8.0.2.

Since the number of affected programs seems quite small, and since the fix
is so straightforward, we opt to simply note this discrepancy in the 8.0.2
release notes.

Resolves #12768.

(cherry picked from commit ead83db8)