[GHC] #7913: Argument order not preserved by nubBy

[GHC]

#7913: Argument order not preserved by nubBy
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              Reporter:  paullik     |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Prelude     |          Version:  7.6.3
            Resolution:              |         Keywords:  nubBy
      Operating System:  Linux       |     Architecture:  Unknown/Multiple
       Type of failure:              |       Difficulty:  Unknown
  None/Unknown                       |       Blocked By:
             Test Case:              |  Related Tickets:
              Blocking:              |
Differential Revisions:              |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"a2e7bbfe7656cf7dbf1af4da5c077ac0b5d41127/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a2e7bbfe7656cf7dbf1af4da5c077ac0b5d41127"
 Preserve argument order to (==)/eq in nub and nubBy

 This makes nub and nubBy behave as specified in the Haskell 98 Report.

 This reverts 0ad9def53842e86fb292eccb810190711c42d7c5, and
 fixes #3280, #7913 and #2528 (properly).

 Before this change, the output of `T2528` was (4x wrong):
 ```
 [A,B]
 [1,2]
 False
 False
 ```

 Reviewed By: dfeuer, ekmett, austin, hvr

 Differential Revision: https://phabricator.haskell.org/D238
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7913#comment:5>
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