rec {} causes "head:empty list" exception

Using GHC HEAD 7.11.20150116 (and before)

Trying to load the following into ghci

{-# LANGUAGE RecursiveDo #-}

bar :: IO ()
bar = do
  rec {}
  return ()

results in

> :load "/home/alanz/mysrc/github/alanz/ghc-exactprint/tests/examples/Foo.hs"
[1 of 1] Compiling Main             ( /home/alanz/mysrc/github/alanz/ghc-exactprint/tests/examples/Foo.hs, interpreted )
*** Exception: Prelude.head: empty list
> 

Trac metadata

Trac field	Value
Version	7.11
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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