[ Filled as RC by a team member to get this package autoremoved from
  testing if nobody disagrees. Please, do downgrade this bug with an
  explanation if you disagree. ]

civicrm-common and php-net-nntp were the last packages depending on
php-log. Both have been removed from Debian a while ago. There is no
point to distribute php-log with Debian anymore, it only wastes QA
efforts.

I intend to follow up with an RM requests in a few months if nobody
objects (but feel free to beat me to it).

Regards,

taffit