Clearly the old code was more elegant (NULL cache indicated "not loaded"),
but it had some drawbacks, so from now on we indicate the state of caches
explicitly.
Old drawbacks:
When we had an empty database (unstable), libalpm called db_populate after
every pkgcache access, because NULL pkgcache indicated "not loaded" state.
This is not a common case, but the same situation can happen with grpcache,
which is more problematic: If the user had a custom repo with no groups,
grpcache was always NULL. (grpcache is also loaded per database.) Thus
every get_grpcache call induced a load_grpcache operation, so the benefits
of grpcache was completely lost.
Signed-off-by: Nagy Gabor <ngaba@bibl.u-szeged.hu>
Signed-off-by: Dan McGee <dan@archlinux.org>
cb7337eb64