Comment # 1 on bug 1219345 from Michael Andres

(In reply to Martin Wilck from comment #0)
> the package has been rebuilt and some checksums don't match, while the
> version/release is the same as before.

That's the issue. It's no longer the same package with the same content but
sill uses the same version-release. OBS should not do this. If the content
changed the build count should be increased.

ZYPP_SINGLE_RPMTRANS most probably gives you the same file conflicts as a
re-install with plain rpm does. That's the purpose of ZYPP_SINGLE_RPMTRANS.

IMO it's not a bug in zypp, but in OBS (unless rpm on the commandline would not
complain)