[GHC] #8083: setNumCapabilities broken in HEAD

[GHC]

#8083: setNumCapabilities broken in HEAD
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        Reporter:  parcs                        |            Owner:
            Type:  bug                          |           Status:  new
        Priority:  normal                       |        Milestone:
       Component:  Runtime System               |          Version:  7.7
      Resolution:                               |         Keywords:
Operating System:  Unknown/Multiple             |     Architecture:
 Type of failure:  Incorrect result at runtime  |  Unknown/Multiple
       Test Case:                               |       Difficulty:
        Blocking:                               |  Unknown
                                                |       Blocked By:
                                                |  Related Tickets:
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Comment (by parcs):

 Even simpler test case:

 {{{
 #!haskell
 import GHC.Conc
 import Control.Monad

 main :: IO ()
 main = do
     n <- getNumCapabilities
     when (n == 1) $ setNumCapabilities 2
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8083#comment:1>
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