Flamethrower turret can be used to connect fluid networks with differnt liquids. The liquid in one of the liquid networks is entirely lost.
See before and after in these screenshots:
It happens always and the game should prevent the build as it does when I try to connect differing liquid networks by other means.
It's always been possible to connect different fluid systems using bots, just place a ghost pipe between two fluid systems and you have them connected.
It shouldn't delete the fluid though, it's still in there if you click the pipe. Just the cleanup isn't that simple anymore, when you separate them again, since 2.0 the fluid will randomly be in one or the other.