AArch64 : Installing 7.10.1 fails

Built 7.10.1 from the release tarball, using ghc-7.6.3 from Debian. Build of the compiler goes fine, but when I install it I get:

"inplace/bin/ghc-cabal" register libraries/ghc-prim dist-install \
    "/home/erikd/GHC/7.10.1/lib/ghc-7.10.1/bin/ghc" \
    "/home/erikd/GHC/7.10.1/lib/ghc-7.10.1/bin/ghc-pkg" \
    "/home/erikd/GHC/7.10.1/lib/ghc-7.10.1" '' '/home/erikd/GHC/7.10.1' \
    '/home/erikd/GHC/7.10.1/lib/ghc-7.10.1' \
    '/home/erikd/GHC/7.10.1/share/doc/ghc/html/libraries' NO  
Warning: cannot determine version of
/home/erikd/GHC/7.10.1/lib/ghc-7.10.1/bin/ghc-pkg :
""
ghc-cabal: libraries/Cabal/Cabal/Distribution/Simple/GHC.hs:1050:5-47: 
    Irrefutable pattern failed for pattern Data.Maybe.Just ver

The code in question is:

hcPkgInfo :: ProgramConfiguration -> HcPkg.HcPkgInfo
hcPkgInfo conf = HcPkg.HcPkgInfo { HcPkg.hcPkgProgram    = ghcPkgProg
                                 , HcPkg.noPkgDbStack    = v < [6,9]
                                 , HcPkg.noVerboseFlag   = v < [6,11]
                                 , HcPkg.flagPackageConf = v < [7,5]
                                 , HcPkg.useSingleFileDb = v < [7,9]
                                 }
  where
    v               = versionBranch ver
    Just ghcPkgProg = lookupProgram ghcPkgProgram conf
    Just ver        = programVersion ghcPkgProg

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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