Comment # 2 on bug 1179521 from Dominique Leuenberger

(In reply to Egbert Eich from comment #1)
> Not sure why netcdf-cxx4 doesn't get rebuilt when a dependency (hdf5) gets
> updated.
> Dominique?

Tumbleweed uses rebuild=local, i.e. only the packages being checked in are
rebuilt (the other modes are too expensive for Tumbleweed)

A rebuild bot then triggers rebuild of stuff that has lost 'install
dependencies'. i.e when a check-in on libFOO 9e.g. hdf5) happens, and pkg
netcdf has a dependency that is no longer satisfied (e.g. libhdf5.so.0 now
called libhdf5.so.1, fictive example), it is being rebuilt.

i.e. we rely on libraries providing proper ABI.

In case a rebuild on specific library versions is required (which in turn
implies either bad checks or somebody not adhering to ABI stability without
changing so-versioning), a package needs to specify that it requires the same
library at runtime as at buildtime (e.g. %requires_eq)

In case the package itself does not 'really' require a specific version but
wants to trigger a rebuilt, a 'pseude package' likekernel-default-base-rebuild
can be created; that package has no other meaning than to instruct the system
that rebulds are needed (it's not meant to be used, but looses its install
depslike any other package would - thus triggering the package for a rebuild)