Impredicativity bug: Church2 test gives a rather confusing error with the HEAD

The Church2 test gives a rather confusing error with the HEAD:

Church2.hs:27:14:
    Couldn't match expected type `CNat'
           against inferred type `(a -> a) -> a -> a'
      Expected type: CNat -> CNat
      Inferred type: CNat -> CNat
    In the first argument of `n', namely `(mul m)'
    In the expression: n (mul m) n1

In particular the lines

      Expected type: CNat -> CNat
      Inferred type: CNat -> CNat

are confusing, and I'm not sure why it's giving two expected/inferred pairs of types.

Trac metadata

Trac field	Value
Version	6.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Unknown
Architecture	Unknown