With 'hosts: mdns4' in nsswitch.conf, getaddrinfo() returns -5 (EAI_NODATA) when network interface is down

When the "hosts:" line in nsswitch.conf includes `mdns4` or `mdns4_minimal` last and the network interface is taken down, getaddrinfo() returns -5 (EAI_NODATA — "No address associated with hostname") instead of something more appropriate such as -4 (EAI_FAIL — "Non-recoverable failure in name resolution").

$ dpkg -l libc6
[...]
ii libc6:amd64 2.17-93ubuntu4 amd64

$ grep hosts /etc/nsswitch.conf
hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

$ sudo su
# ifconfig eth0 down
# ./a.out
Making resolv.conf empty
Results of looking up www.google.com: status = -5, errno = 110
Results of looking up a bogus name: status = -5, errno = 110
Writing correct nameserver option to resolv.conf
Results of looking up www.google.com: status = -5, errno = 110
Results of looking up a bogus name: status = -5, errno = 110
Writing incorrect nameserver option to resolv.conf
Results of looking up www.google.com: status = -5, errno = 110
Results of looking up a bogus name: status = -5, errno = 110

# cat x.c
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <errno.h>
#include <stdio.h>

struct addrinfo *res;

void check_google()
{
    int status;
    status = getaddrinfo("www.google.com", NULL, NULL, &res);
    printf("Results of looking up www.google.com: status = %d, errno = %d\n", status, errno);
    status = getaddrinfo("sjfkdsjfswfloo0f02938sjf28398sd.com", NULL, NULL, &res);
    printf("Results of looking up a bogus name: status = %d, errno = %d\n", status, errno);
}

int main()
{
    FILE *fp;

    printf("Making resolv.conf empty\n");
    fp = fopen("/etc/resolv.conf", "w+"); fclose(fp);
    sleep(1);
    check_google();

    printf("Writing nameserver option to resolv.conf\n");
    fp = fopen("/etc/resolv.conf", "w+"); fprintf(fp, "nameserver 193.67.79.39\n"); fclose(fp);
    sleep(1);
    check_google();

    printf("Writing incorrect nameserver option to resolv.conf\n");
    fp = fopen("/etc/resolv.conf", "w+"); fprintf(fp, "nameserver 192.168.5.4\n"); fclose(fp);
    sleep(1);
    check_google();
}