Hello devs,

I noticed that in ghc/GHCi/UI.hs, the calls to 'revertCAFs' are made in the compiler's RTS instead of the interpreter's RTS. When -fexternal-interpreter is on this distinction is visible, otherwise they are one and the same so it works as intended.

Shouldn't there be a RevertCAFs data constructor in `libraries/ghci/GHCi/Message.hs` to tell the interpreter process to revert the CAFs in its heap?