So far as 7/29/2016 for swift version 2.9.1.dev51
According to the official guide here http://docs.openstack.org/developer/swift/development_saio.html , there will be some mismatch packages fail you on installation.
Which means , there are some preparation work you have to do before you follow the official guide,here are steps that I overcome problems:
1.Install epel-relase and centos-mitaka package, this is almost a must for using higher version python
#yum install epel-release centos-release-openstack-mitaka -y
#yum update -y
The key is , you have to install RDO-openstack package , it will basically help you to install all required packages that openstack swift needs , and yes , correct version
Now you should be able to follow the guide without problem