Many applications include a python interpreter, so now when I try to run a program, Subversion's 2.5 interpreter is used to execute it.
I've already changed environment path order, putting subversion's last.
Now when I run python from command line, the 2.7 is run, but when I pass the script's filename, version 2.5 seems to be running it, as a few exceptions reveal the path.
So specifically, python 2.7 tries to imports module from subversions path.
If you are having problems with PATH in windows, set the one you want to use at the start of the path variable. Plus, you might want to use User variables instead of system ones.
But I don't know if that answers your question because you didn't really ask anything.
Python interpreter path search order on windows