[GHC] #12485: -package-db flags now need to be sorted by dependency order

[GHC]

#12485: -package-db flags now need to be sorted by dependency order
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        Reporter:  niteria           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.3
       Component:  Package system    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  phab:D2450,
       Wiki Page:                    |  phab:D2514
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Comment (by ezyang):

 FWIW, in #12518 Harendra wants to bring back erroring, but guarded by a
 flag ;)

 Note about timeline: I'm unlikely to be able to patchfix the quick
 workaround before the end of ICFP (on vacation). I can handle adding ABI
 hashes to depends though for 8.2.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12485#comment:22>
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