### Please describe the problem.

I have an old (broken) annex that I would like to revive. I'm unable to upgrade the annex.

### What steps will reproduce the problem?

git annex sync
git-annex: Repository /mnt/sdc/annex/.git is at unsupported version 9. Automatic upgrade exception! .git/annex: createDirectory: does not exist (No such file or directory)

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

git-annex version: 10.20230626-g55fef4fb81
running on Archlinux (up to date)

### Please provide any additional information below.

[[!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

[alex@proliant .git]$ git annex sync
git-annex: Repository /mnt/sdc/annex/.git is at unsupported version 9. Automatic upgrade exception! .git/annex: createDirectory: does not exist (No such file or directory)
[alex@proliant .git]$ git annex upgrade
upgrade  (v9 to v10...) 
git-annex: .git/annex: createDirectory: does not exist (No such file or directory)
failed
upgrade: 1 failed

# 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)

I'm starting to get the hang of git-annex (after about three years ;-). I started with an annex which I somehow broke. Then I opened a "bannex", which I thought I broke. Therefore I started "cannex", only to realize that bannex wasn't broke. Now I'm using bannex, but my data is scattered around a-,b-,c-annex. I think I made Napoleon somewhere in between (because he annexed Europe). But my brain is slowly wrapping around git and the annex. I'd like to create an annex to rule them all ;-)
Thanks to the developers!