Upgrading kamal from `v1.8.3` to `v1.9.0` broke my [kamal playground](https://labs.iximiuz.com/playgrounds/kamal):
```
laborant@dev-machine:~/svc-a$ kamal setup
INFO [34d0def6] Running /usr/bin/env mkdir -p .kamal on 172.16.0.3
INFO [c34cf833] Running /usr/bin/env mkdir -p .kamal on 172.16.0.4
INFO [34d0def6] Finished in 0.147 seconds with exit status 0 (successful).
INFO [c34cf833] Finished in 0.204 seconds with exit status 0 (successful).
Acquiring the deploy lock...
Ensure Docker is installed...
INFO [413ee426] Running docker -v on 172.16.0.4
INFO [f1acacba] Running docker -v on 172.16.0.3
INFO [413ee426] Finished in 0.036 seconds with exit status 0 (successful).
INFO [f1acacba] Finished in 0.076 seconds with exit status 0 (successful).
Log into image registry...
INFO [94cff492] Running docker login registry.iximiuz.com -u [REDACTED] -p [REDACTED] on localhost
INFO [94cff492] Finished in 0.077 seconds with exit status 0 (successful).
INFO [605c535f] Running docker login registry.iximiuz.com -u [REDACTED] -p [REDACTED] on 172.16.0.4
INFO [6002b598] Running docker login registry.iximiuz.com -u [REDACTED] -p [REDACTED] on 172.16.0.3
INFO [605c535f] Finished in 0.083 seconds with exit status 0 (successful).
INFO [6002b598] Finished in 0.083 seconds with exit status 0 (successful).
Build and push app image...
INFO [9d172b1e] Running docker --version && docker buildx version on localhost
INFO [9d172b1e] Finished in 0.059 seconds with exit status 0 (successful).
INFO Cloning repo into build directory `/tmp/kamal-clones/svc-a-2f65914456263/workdir/`...
INFO [26fb1bd3] Running /usr/bin/env git -C /tmp/kamal-clones/svc-a-2f65914456263 clone /workdir --recurse-submodules on localhost
ERROR Error preparing clone: Failed to clone repo: git exit status: 32768
git stdout: Nothing written
git stderr: Cloning into 'workdir'...
fatal: detected dubious ownership in repository at '/workdir/.git'
To add an exception for this directory, call:
git config --global --add safe.directory /workdir/.git
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
, deleting and retrying...
INFO Cloning repo into build directory `/tmp/kamal-clones/svc-a-2f65914456263/workdir/`...
INFO [fd4aac0c] Running /usr/bin/env git -C /tmp/kamal-clones/svc-a-2f65914456263 clone /workdir --recurse-submodules on localhost
Finished all in 0.3 seconds
Releasing the deploy lock...
Finished all in 0.6 seconds
ERROR (SSHKit::Command::Failed): git exit status: 32768
git stdout: Nothing written
git stderr: Cloning into 'workdir'...
fatal: detected dubious ownership in repository at '/workdir/.git'
To add an exception for this directory, call:
git config --global --add safe.directory /workdir/.git
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
laborant@dev-machine:~/svc-a$ kamal version
2.0.0
```
I checked the [v1.8.3...v1.9.0](https://github.com/basecamp/kamal/compare/v1.8.3...v1.9.0) diff, and couldn't find anything even remotely related to the above error.
Then I checked the `git` versions in kamal `v1.8.3` and `v1.9.0` images:
```
docker run -it --rm --entrypoint sh ghcr.io/basecamp/kamal:v1.8.3
/workdir # git --version
git version 2.38.5
```
vs.
```
docker run -it --rm --entrypoint sh ghcr.io/basecamp/kamal:v2.0.0
/workdir # git --version
git version 2.39.5
```
Apparently, something changed in between `2.38.5` and `2.39.5` git releases (likely yet another CVE fix), and the `git config --global --add safe.directory /workdir` stopped working.
Here is the mitigation I currently use, but it's a bit awkward to do it:
```
docker build -t ghcr.io/basecamp/kamal:v2.0.0 - <<EOF
FROM ghcr.io/basecamp/kamal:v2.0.0
RUN git config --global --add safe.directory /workdir/.git
EOF
```
Hence, this PR.
To repro, you can start a [kamal playground](https://labs.iximiuz.com/playgrounds/kamal), then `docker pull ghcr.io/basecamp/kamal:v2.0.0` to override my patched image, and `cd svc-a && kamal setup`.
