Inconsistent Behavior of TFieldPath and nullptr comparison

Commit 6448c6f (https://github.com/EpicGames/UnrealEngine/commit/6448c6f6d1de1e9fac9614248e06ba06b837814d) introduced inconsistent behavior for TFieldPath and nullptr comparison, depending on constness of the TFieldPath reference.

Run the following code within unreal, notice that constTest and nonConstTest have different results:

TFieldPath<FProperty> tempVar

;
bool constTest = (const TFieldPath<FProperty>&)tempVar == nullptr;
bool nonConstTest = tempVar == nullptr;
ensure(constTest == nonConstTest);