### Please describe the problem.
The build fails with GHC 8.4.3

### What steps will reproduce the problem?
Be sure to use esqueleto HEAD to avoid getting stuck on dependencies.

### What version of git-annex are you using? On what operating system?
git-annex-6.20180529 on macOS

### Please provide any additional information below.

[[!format sh """
==> cabal install --jobs=8 --max-backjumps=100000 --prefix=/usr/local/Cellar/git-annex/6.20180529 --flags=s3 webapp
clang: warning: -Wl,-headerpad_max_install_names: 'linker' input unused
clang: warning: argument unused during compilation: '-L/usr/local/opt/gettext/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/libffi/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/icu4c/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/openssl/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/readline/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/sqlite/lib'
clang: warning: argument unused during compilation: '-L/usr/local/lib'
clang: warning: argument unused during compilation: '-L/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries'
Resolving dependencies...
Notice: installing into a sandbox located at
/private/tmp/git-annex-20180529-26197-14ebtme/git-annex-6.20180529/.cabal-sandbox
Configuring git-annex-6.20180529...
Building git-annex-6.20180529...
Failed to install git-annex-6.20180529
Build log ( /private/tmp/git-annex-20180529-26197-14ebtme/git-annex-6.20180529/.cabal-sandbox/logs/ghc-8.4.3/git-annex-6.20180529-9O50etRsVNH1q2HUlIF2Gu.log ):
cabal: Entering directory '.'
[ 1 of 34] Compiling Utility.Applicative ( Utility/Applicative.hs, dist/dist-sandbox-669b35af/setup/Utility/Applicative.o )
[ 2 of 34] Compiling Utility.Data     ( Utility/Data.hs, dist/dist-sandbox-669b35af/setup/Utility/Data.o )
[ 3 of 34] Compiling Utility.Exception ( Utility/Exception.hs, dist/dist-sandbox-669b35af/setup/Utility/Exception.o )
[ 4 of 34] Compiling Utility.Env.Basic ( Utility/Env/Basic.hs, dist/dist-sandbox-669b35af/setup/Utility/Env/Basic.o )
[ 5 of 34] Compiling Build.Mans       ( Build/Mans.hs, dist/dist-sandbox-669b35af/setup/Build/Mans.o )
[ 6 of 34] Compiling Utility.FileSize ( Utility/FileSize.hs, dist/dist-sandbox-669b35af/setup/Utility/FileSize.o )
[ 7 of 34] Compiling Utility.Misc     ( Utility/Misc.hs, dist/dist-sandbox-669b35af/setup/Utility/Misc.o )
[ 8 of 34] Compiling Utility.Monad    ( Utility/Monad.hs, dist/dist-sandbox-669b35af/setup/Utility/Monad.o )
[ 9 of 34] Compiling Utility.PartialPrelude ( Utility/PartialPrelude.hs, dist/dist-sandbox-669b35af/setup/Utility/PartialPrelude.o )
[10 of 34] Compiling Utility.Process.Shim ( Utility/Process/Shim.hs, dist/dist-sandbox-669b35af/setup/Utility/Process/Shim.o )
[11 of 34] Compiling Utility.Process  ( Utility/Process.hs, dist/dist-sandbox-669b35af/setup/Utility/Process.o )
[12 of 34] Compiling Utility.Network  ( Utility/Network.hs, dist/dist-sandbox-669b35af/setup/Utility/Network.o )
[13 of 34] Compiling Utility.Split    ( Utility/Split.hs, dist/dist-sandbox-669b35af/setup/Utility/Split.o )
[14 of 34] Compiling Utility.SafeCommand ( Utility/SafeCommand.hs, dist/dist-sandbox-669b35af/setup/Utility/SafeCommand.o )
[15 of 34] Compiling Utility.ExternalSHA ( Utility/ExternalSHA.hs, dist/dist-sandbox-669b35af/setup/Utility/ExternalSHA.o )
[16 of 34] Compiling Utility.FileSystemEncoding ( Utility/FileSystemEncoding.hs, dist/dist-sandbox-669b35af/setup/Utility/FileSystemEncoding.o )
[17 of 34] Compiling Utility.SystemDirectory ( Utility/SystemDirectory.hs, dist/dist-sandbox-669b35af/setup/Utility/SystemDirectory.o )
[18 of 34] Compiling Utility.Tmp      ( Utility/Tmp.hs, dist/dist-sandbox-669b35af/setup/Utility/Tmp.o )
[19 of 34] Compiling Utility.Directory ( Utility/Directory.hs, dist/dist-sandbox-669b35af/setup/Utility/Directory.o )
[20 of 34] Compiling Build.Version    ( Build/Version.hs, dist/dist-sandbox-669b35af/setup/Build/Version.o )
[21 of 34] Compiling Utility.UserInfo ( Utility/UserInfo.hs, dist/dist-sandbox-669b35af/setup/Utility/UserInfo.o )
[22 of 34] Compiling Utility.Path     ( Utility/Path.hs, dist/dist-sandbox-669b35af/setup/Utility/Path.o )
[23 of 34] Compiling Common           ( Common.hs, dist/dist-sandbox-669b35af/setup/Common.o )
[24 of 34] Compiling Utility.DottedVersion ( Utility/DottedVersion.hs, dist/dist-sandbox-669b35af/setup/Utility/DottedVersion.o )
[25 of 34] Compiling Git.Version      ( Git/Version.hs, dist/dist-sandbox-669b35af/setup/Git/Version.o )
[26 of 34] Compiling Build.TestConfig ( Build/TestConfig.hs, dist/dist-sandbox-669b35af/setup/Build/TestConfig.o )
[27 of 34] Compiling Build.Configure  ( Build/Configure.hs, dist/dist-sandbox-669b35af/setup/Build/Configure.o )
[28 of 34] Compiling Utility.OSX      ( Utility/OSX.hs, dist/dist-sandbox-669b35af/setup/Utility/OSX.o )
[29 of 34] Compiling Utility.FreeDesktop ( Utility/FreeDesktop.hs, dist/dist-sandbox-669b35af/setup/Utility/FreeDesktop.o )
[30 of 34] Compiling Config.Files     ( Config/Files.hs, dist/dist-sandbox-669b35af/setup/Config/Files.o )
[31 of 34] Compiling Assistant.Install.Menu ( Assistant/Install/Menu.hs, dist/dist-sandbox-669b35af/setup/Assistant/Install/Menu.o )
[32 of 34] Compiling Assistant.Install.AutoStart ( Assistant/Install/AutoStart.hs, dist/dist-sandbox-669b35af/setup/Assistant/Install/AutoStart.o )
[33 of 34] Compiling Build.DesktopFile ( Build/DesktopFile.hs, dist/dist-sandbox-669b35af/setup/Build/DesktopFile.o )
[34 of 34] Compiling Main             ( dist/dist-sandbox-669b35af/setup/setup.hs, dist/dist-sandbox-669b35af/setup/Main.o )
Linking ./dist/dist-sandbox-669b35af/setup/setup ...
  checking version...fatal: Not a git repository (or any of the parent directories): .git
 6.20180529
  checking UPGRADE_LOCATION... not available
  checking git... yes
  checking git version... 2.10.1 (Apple Git-78)
  checking cp -a... yes
  checking cp -p... yes
  checking cp --preserve=timestamps... no
  checking cp --reflink=auto... no
  checking xargs -0... yes
  checking rsync... yes
  checking curl... yes
  checking bup... no
  checking nice... yes
  checking ionice... no
  checking nocache... no
  checking gpg... not available
  checking lsof... lsof
  checking git-remote-gcrypt... not available
  checking ssh connection caching... yes
  checking sha1... not available
  checking sha256... not available
  checking sha512... not available
  checking sha224... not available
  checking sha384... not available
Configuring git-annex-6.20180529...
clang: warning: -Wl,-headerpad_max_install_names: 'linker' input unused
clang: warning: argument unused during compilation: '-L/usr/local/opt/gettext/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/libffi/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/icu4c/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/openssl/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/readline/lib'
clang: warning: argument unused during compilation: '-L/usr/local/opt/sqlite/lib'
clang: warning: argument unused during compilation: '-L/usr/local/lib'
clang: warning: argument unused during compilation: '-L/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries'
Preprocessing executable 'git-annex' for git-annex-6.20180529..
Building executable 'git-annex' for git-annex-6.20180529..
[  1 of 593] Compiling Assistant.Types.BranchChange ( Assistant/Types/BranchChange.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Assistant/Types/BranchChange.o )
[  2 of 593] Compiling Assistant.Types.ThreadName ( Assistant/Types/ThreadName.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Assistant/Types/ThreadName.o )
[  3 of 593] Compiling Assistant.Types.TransferSlots ( Assistant/Types/TransferSlots.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Assistant/Types/TransferSlots.o )
[  4 of 593] Compiling BuildFlags       ( BuildFlags.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/BuildFlags.o )
[  5 of 593] Compiling BuildInfo        ( BuildInfo.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/BuildInfo.o )
[  6 of 593] Compiling Build.BundledPrograms ( Build/BundledPrograms.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Build/BundledPrograms.o )
[  7 of 593] Compiling Config.Cost      ( Config/Cost.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Config/Cost.o )
[  8 of 593] Compiling Logs.Line        ( Logs/Line.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Logs/Line.o )
[  9 of 593] Compiling Types.Availability ( Types/Availability.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Types/Availability.o )
[ 10 of 593] Compiling Types.BranchState ( Types/BranchState.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Types/BranchState.o )
[ 11 of 593] Compiling Types.Concurrency ( Types/Concurrency.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Types/Concurrency.o )
[ 12 of 593] Compiling Types.Creds      ( Types/Creds.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Types/Creds.o )
[ 13 of 593] Compiling Assistant.Types.CredPairCache ( Assistant/Types/CredPairCache.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Assistant/Types/CredPairCache.o )
[ 14 of 593] Compiling Types.DesktopNotify ( Types/DesktopNotify.hs, dist/dist-sandbox-669b35af/build/git-annex/git-annex-tmp/Types/DesktopNotify.o )

Types/DesktopNotify.hs:19:10: error:
    • No instance for (Semigroup DesktopNotify)
        arising from the superclasses of an instance declaration
    • In the instance declaration for ‘Monoid DesktopNotify’
   |
19 | instance Monoid DesktopNotify where
   |          ^^^^^^^^^^^^^^^^^^^^
cabal: Leaving directory '.'
cabal: Error: some packages failed to install:
git-annex-6.20180529-9O50etRsVNH1q2HUlIF2Gu failed during the building phase.
The exception was:
ExitFailure 1
"""]]

Full log https://gist.github.com/ilovezfs/e3af135ed0362e0253a786c71f2a914f

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

Yes! Thanks :)

> Consequence of the Semigroup Monoid change. Fixed. [[done]] --[[Joey]]

