[vers manager] minor fix to support python2.6

On CentOS 6.*, Python2.6 is the primary variant of python available through the package manager. Unfortunately, it is very cumbersome to install a newer version of Python, as several systems tools (such as yum) have a hard dependency on the older version. Because of this we run into compatibility problems:

Python2.6 does not support dict comprehensions (these were introduced in python2.7 - see PEP274). We use this in two places within the version script. This patch changes the comprehensions into normal loop operations. This works fine with later versions of Python2.* branch.

It's unfortunate that we need to worry about this given that python2.6 is no longer support by the Python devs... perhaps we should rethink out position on supporting CentOS 6.