### Please describe the problem.
Build error 1 during build process of git-annex on alpine 5.15 using GHC 9.0.1.

### What steps will reproduce the problem?
Build git-annex on alpine 5.15 using following APKBUILD:
https://github.com/ayakael/aports/blob/testing/git-annex/testing/git-annex/APKBUILD

### What version of git-annex are you using? On what operating system?
git-annex: 20211123
os: alpine linux 5.15
ghc: 9.0.1
cabal: 3.6.2.0

### Please provide any additional information below.
I made an attempt of fixing by reverting the first fix attempt done on line 181 by commit 2739adc. It gave the same error, but it is most likely related. I know very little of haskell, thus could not push the debugging further.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log
[411 of 670] Compiling Remote.Glacier   ( Remote/Glacier.hs, /var/build/aports/testing/git-annex/src/git-annex-8.20211123/dist-newstyle/build/x86_64-linux/ghc-9.0.1/git-annex-8.20211123/build/git-annex/git-annex-tmp/Remote/Glacier.o, /var/build/aports/testing/git-annex/src/git-annex-8.20211123/dist-newstyle/build/x86_64-linux/ghc-9.0.1/git-annex-8.20211123/build/git-annex/git-annex-tmp/Remote/Glacier.dyn_o )

Remote/Glacier.hs:179:12: error:
    • Couldn't match type: Key
                           -> MeterUpdate
                           -> Maybe Utility.Hash.IncrementalVerifier
                           -> (ContentSource -> Annex a0)
                           -> Annex a0
                     with: forall a.
                           Key
                           -> MeterUpdate
                           -> Maybe Utility.Hash.IncrementalVerifier
                           -> (ContentSource -> Annex a)
                           -> Annex a
      Expected: Remote -> Retriever
        Actual: Remote
                -> Key
                -> MeterUpdate
                -> Maybe Utility.Hash.IncrementalVerifier
                -> (ContentSource -> Annex a0)
                -> Annex a0
    • In the expression: byteRetriever . retrieve'
      In an equation for ‘retrieve’: retrieve = byteRetriever . retrieve'
    |
179 | retrieve = byteRetriever . retrieve'
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^
make: *** [Makefile:58: git-annex] Error 1
# End of transcript or log.
"""]]

### 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)
Oh absolutely. This version compiles fine under alpine 5.14, which uses GHC 8.8.4. I've been using this software for many years without major issues, and it's a linchpin of my backup infrastructure. Thanks for the all the good work!

> [[fixed|done]] --[[Joey]]
