[GHC] #11782: Teach ghc-pkg to read multiple registrations from command line

[GHC]

#11782: Teach ghc-pkg to read multiple registrations from command line
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           Reporter:  ezyang         |             Owner:
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  ghc-pkg        |           Version:  8.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 ghc-pkg register and ghc-pkg update should take files/stdin streams which
 consist of multiple packages separated by `----`. ghc-pkg will operate
 atomically: either all of the registrations succeed or none are performed.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11782>
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