[GHC] #9117: Coercible constraint solver misses one

[GHC]

#9117: Coercible constraint solver misses one
-------------------------------------+------------------------------------
        Reporter:  goldfire          |            Owner:  nomeata
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------

Comment (by nomeata):

 Started http://www.haskell.org/haskellwiki/GHC/Coercible and added the
 bits about how to achieve different `Coercible` behaviour in internal and
 external code.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9117#comment:20>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler