Panic in ghci name suggestion

From a plain invocation of ghci:

$ ghci
GHCi, version 7.2.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Prelude> 2
2
Prelude> fit

<interactive>:0:1:ghc: panic! (the 'impossible' happened)
  (GHC version 7.2.1 for x86_64-apple-darwin):
	unknownNameSuggestErr UnhelpfulSpan

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Prelude>

Presumably, ghci wants to suggest the it variable but is getting confused because that variable wasn't defined in a source file.

Note that this doesn't actually crash ghci; the prompt resumes as normal after the error message is printed out.

Trac metadata

Trac field	Value
Version	7.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture