Ok, I started simply by *moving* code, without additionnal changes. I will watch for buildbots to ensure that no regression was added. The Lib/test/regrtest.py is kept to not break any existing tool. It looks like Lib/test/regrtest.py is very important in Python, much more than what I expected. It's used for PGO compilation, it's used by various scripts for different platforms, it's used in scripts to build Linux packages,etc.

I used "hg cp" to create new files to ensure that the history is not lost.

I will write new patches for the real refactoring work described in the first message. It will be much easier to review changes written after the code was moved. So we can discuss controversal changes like the creation of a class for libregrtest/main.py ;-)