[GHC] #16038: Simplifier incorrectly breaks recursive groups

[GHC]

#16038: Simplifier incorrectly breaks recursive groups
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        Reporter:  osa1              |                Owner:  osa1
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Well that was harder than I expected!

 Done now, thought.

 Omer: could you add a test?  I'll leave it open for that reason.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16038#comment:6>
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