nss-db is due for removal due to bug 324017. It appears that the functionality of nss-db has been rolled into glibc from glibc-2.15 onwards. Please check if glibc can function as a drop-in replacement for nss-db so that I can get nss-db removed soon.
The glibc nss_db is not compatible, and the nsscache author doesn't really support the nssdb backend anyway. https://github.com/google/nsscache/issues/28 I masked the nssdb use flag on net-nds/nsscache.