Metavariable leakage through Template Haskell reification

Using reify on a variable defined in the same module results in metavariables reported to the user.

{-# LANGUAGE TemplateHaskell #-}

import Language.Haskell.TH
import Language.Haskell.TH.Ppr

aNumber = 5

do VarI name1 t1 _ <- reify 'aNumber
   runIO . print $ ppr_sig name1 t1
   return []

Loading the code above code in GHCi produces the following output:

Main.aNumber :: p_0

What is p_0? I would expect the reified type to match what :t +v reports:

*Main> :t +v aNumber
aNumber :: Integer

In this particular case, disabling the monomorphism restriction fixes the issue:

{-# LANGUAGE NoMonomorphismRestriction #-}

Now the following reified type is printed:

Main.aNumber :: forall (p_0 :: *) . GHC.Num.Num p_0 => p_0

And it does match what :t +v reports:

*Main> :set -fprint-explicit-foralls 
*Main> :t +v aNumber
aNumber :: forall {p}. Num p => p

The same issue affects reifyType and the regression test should test both reify & reifyType.