[GHC] #13375: ghc-pkg "cache is out of date" message breaks testsuite

[GHC]

#13375: ghc-pkg "cache is out of date" message breaks testsuite
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  highest           |            Milestone:  8.2.1
       Component:  ghc-pkg           |              Version:  8.0.1
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by marinelli):

 Here they are:

 {{{
 $ mkdir -p /tmp/ghc
 $ wget -q -P /tmp/ghc/
 'https://downloads.haskell.org/~ghc/8.2.1-rc2/ghc-8.2.0.20170507-x86_64-deb8-linux.tar.xz'
 $ cd /tmp/ghc/
 $ tar xf ghc-8.2.0.20170507-x86_64-deb8-linux.tar.xz
 $ cd ./ghc-8.2.0.20170507/
 $ sh configure --prefix=/opt/ghc
 $ make install
 $ env PATH=/opt/ghc/bin:$PATH ghc --version
 The Glorious Glasgow Haskell Compilation System, version 8.2.0.20170507
 $ env PATH=/opt/ghc/bin:$PATH ghc-pkg list
 WARNING: cache is out of date:
 /opt/ghc/lib/ghc-8.2.0.20170507/package.conf.d/package.cache
 ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix.
 /opt/ghc/lib/ghc-8.2.0.20170507/package.conf.d
     Cabal-2.0.0.0
     array-0.5.1.2
 ---✂---
 }}}

 The file config.log is here
 https://gist.github.com/anonymous/05fc2191ffd6a49eb8f3108b17d07d51

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13375#comment:9>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler