Message 266778 - Python tracker

The version conflict problem is why I reverted changing 'extension names' to match the new file names, before rebase collapsing my patches.  I was really glad most were in a separate patch.

Each time a feature ceases to be an extension, the (old) extension name will have to be added to a set of names ignored when calculating the set of extensions.  I will start with one until I have worked out and tested the details.