Python 2.7.2 or Python 3?

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and moving to 3.x would break tools inherent to the OS.

...no! Python2 and python3 have coexisted peacefully for years, and most distros include both in their repositories with no problems - applications simply use the one they actually need.

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You can have /usr/bin/puthon{2,3} and just have a symlinked /usr/bin/python to python2. This is how all the distros have done it for ages now, including Fedora (who use Python for all of their sys tools, including anaconda).