pkg/vcs: dubious ownership errors

[dvyukov]

From https://groups.google.com/g/syzkaller/c/uXATSieF2UI by @mzyngier:

I can't seem to get syzkaller to go and test a branch in response to a
report (12b178b7c756664d2518). The message I sent was:

#syz test: git://[git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git](http://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git) e2631e0328903f6e9711e4c253f2a855a167435b

I also tested

#syz test: git://[git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git](http://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git) kvm-arm64/no-lazy-vgic-init

In both cases, I was told that the checkout had failed, which I find
puzzling... I assume I must be doing something wrong. Could you please
let me know what? Response from the bot attached for reference.

There is some issue with the checkout on the machine:

root@ci-qemu2:/syzkaller/jobs/linux/kernel# git remote -v
fatal: detected dubious ownership in repository at '/syzkaller/jobs/linux/kernel'
To add an exception for this directory, call:
	git config --global --add safe.directory /syzkaller/jobs/linux/kernel

Action items:

1. Understand why the repo is in the dubious state, and fix if there is a problem somewhere.
2. Make the checkout repair procedure detect and fix this.
3. Include verbose output in this and possible other errors.