Hi RMs,

[ Reason ]
There is a flaw in the 'patch' utility that may allow arbitrary file
creation outside the intended working directory. This bug is marked as
no-DSA by the security team, but I would like to fix this anyway.

[ Impact ]
With automation workflows or when the user doesn't take close
attention, this can cause security issues. With a simple additional
check this is prevented.

[ Tests ]
The update adds two self-tests that check if this fix works as
expected. The previous self-tests pass as well at build time.

[ Risks ]
Basically nothing. The fix is small and straightforward. Self-testing
checks some common functionality already.

[ Checklist ]
[x] *all* changes are documented in the d/changelog
[x] I reviewed all changes and I approve them
[x] attach debdiff against the package in stable
[x] the issues are verified as fixed in unstable

Thanks,
Laszlo/GCS