[Haskell] Linking Multiple Versions of the Same Package

[Ashley Yakeley]

I tried doing this out of curiosity. Package B links to version 0.1 of 
open-witness, while package C links to B and version 0.1.1 of open-witness.

Cabal stopped me when doing "cabal configure" in C:

   $ cabal configure
   Configuring C-0.1...
   Warning: This package indirectly depends on multiple versions of the same
   package. This is highly likely to cause a compile failure.
   package B-0.1 requires open-witness-0.1
   package C-0.1 requires open-witness-0.1.1

It appears the issue is that package versions are not recorded in 
External Core names. Thus