getaddrinfo() call does not return both IPv6 and IPv4 addresses if nscd is used, unless cache is invalidated manually

Issue

• Name service caching problem(s)
• On both RHEL 6.2 and 6.4, nscd fails to read or return more than one address family from /etc/hosts upon initialisation/population of its database.
• As an example, stop nscd, clear out its DB, start it and then run a getaddrinfo() call for AF_UNSPEC for localhost. This should return both 127.0.0.1 and ::1 but you only get 127.0.0.1.
• Invalidate the cache with "nscd -i hosts" and try the getaddrinfo() call again, now you get both addresses.
• Potentially related BZ, 576801.