DNS resolution fails after resolv.conf update

[Stanislav Baiduzhyi]

Hi All,

We are facing an issue with DNS server caching on RHEL-based distros: after 
the update of resolv.conf java application cannot resolve the hosts any more.

Reproducer is very simple:
1. Clean /etc/resolv.conf or connect to vpn and use vpn-only nameserver.
2. Launch the minimal java app [1].
3. Restore the /etc/resolv.conf or disconnect from vpn (/etc/resolv.conf 
should be updated with accessible nameserver at this moment).
4. Notice that name resolution continues to fail.

I've prepared a small webrev that fixes the issue [2], but would like to hear 
some ideas/criticism first. If the patch looks ok to everyone, please create 
an issue for this, and I will submit it for approval/sponsorship.

[1]: 
https://e61b615da46327c9050d624b0a3783ba21c6b125.googledrive.com/host/0B5Kp-cB1sXJrfnZ4NHZ0S1V3UTJZcDFra3RwUFZjQXY5WVZzUkwtTTd0Z1IyR1JmbDZPSVk/resolvconf-reinit/ResolvingHost.java

[2]:
https://e61b615da46327c9050d624b0a3783ba21c6b125.googledrive.com/host/0B5Kp-cB1sXJrfnZ4NHZ0S1V3UTJZcDFra3RwUFZjQXY5WVZzUkwtTTd0Z1IyR1JmbDZPSVk/resolvconf-reinit/

-- 
Regards,
    Stas