Allow breakpoints and single-stepping for functions defined interactively

Steps to reproduce (from ghc-HEAD sources for 25 May 2007):

Prelude> let fib n = if n < 2 then 1 else fib (n-1) + fib (n-2)
Prelude> let main = print $ fib 30
Prelude> :break fib
ghc-6.7.20070515: panic! (the 'impossible' happened)
  (GHC version 6.7.20070515 for i386-unknown-linux):
        nameModule fib{v apa}

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

Prelude>

Trac metadata

Trac field	Value
Version	6.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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