By default the periodic updatedb process also incluses Swift storage files, and this affects performance quite a bit. It's likely that this is not required, thus excluding the default path /srv/node from the updatedb process is probably a good idea.
PRUNEPATHS="... /tmp ... /var/spool ... /srv/node"
Submitted upstream doc change: https://review.openstack.org/194126
A note to the manual setup guide (https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux_OpenStack_Platform/6/html/Deploying_OpenStack_Learning_Environments/index.html) should be added as well.
Let's have mlocate maintainer to consider this request.
BTW, the names look sorted, so /srv/node goes between /sfc and /tmp.
This seems to me as something admin should deliberately configure, not a default. /srv/node is not necessarily Swift. A lot of things can be under /srv/node. Especially with the popularity of node.js, people might really want /srv/node indexed. The world is bigger than just OpenStack.
As an operating system distribution, RHEL is not supposed to impose structure on /srv.
(after consultation with msekleta): A setup where you want *some* nodes indexed is also imaginable. /srv/node seems to be too general.