[GHC] #10426: matchGroupArity panic with PatternSynonyms

[GHC]

#10426: matchGroupArity panic with PatternSynonyms
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        Reporter:  Iceland_jack      |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.1
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  T10426
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1665
       Wiki Page:                    |
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Changes (by mpickering):

 * status:  new => patch
 * differential:   => Phab:D1665


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10426#comment:4>
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