Implement Fallback for cpsources.conf

By default, cPanel & WHM servers retrieve updates directly from Public FastUpdate "httpupdate.cpanel.net" but sometime hosting company to reduce the update time, latency, bandwidth create Private FastUpdate Mirror.

The hoster do something like this:

1. grep -q 'planethoster.net' /etc/cpsources.conf || echo "HTTPUPDATE=fastupdate.cp.planethoster.net" > /etc/cpsources.conf

However for any reason if this internal server is down, the upcp process wait 3600 seconds and after stop...:

1. [2016-10-03 14:39:16 -0400] Detected version '11.58.0.31' from version file.
   
   

   [2016-10-03 14:39:16 -0400] Running version '11.58.0.31' of updatenow.

   
   

   [2016-10-03 14:39:16 -0400] Using mirror '199.188.222.163' for host 'fastupdate.cp.ca.planethoster.net'.

   
   

   [2016-10-03 15:39:30 -0400] ***** FATAL: Unable to retrieve tier version info: Failed to download URL 'http://fastupdate.cp.ca.planethoster.net/cpanelsync/TIERS.asc'.

   [2016-10-03 15:39:30 -0400] The Administrator will be notified to review this output when this script completes

   
   

   => Log closed Mon Oct 3 15:39:30 2016

   
   

   [2016-10-03 15:39:30 -0400] 17% complete

   
   

   [2016-10-03 15:39:30 -0400] E Running

   `/usr/local/cpanel/scripts/updatenow --upcp

   --log=/var/cpanel/updatelogs/update.1475519956.log` failed, exited with

   code 255 (signal = 0)

   
   

   => Log closed Mon Oct 3 15:39:31 2016

As a cPanel & WHM server administrator and webhosting provider I would like cPanel to offer a fallback option that I can enable: if the defined server is not available, move on to the next one listed.

1. If HTTPUPDATE is down
2. --> not kill upcp; instead use httpupdate.cpanel.net