[docs] [issue15521] Dev Guide should say how to run tests in 2.7

Chris Jerdonek added the comment: It is a relatively large section (nine paragraphs + six code snippets) and is primarily about the in-development branch, so I did not want to interrupt the flow with a remark specific to 2.7. I also liked that the instructions in a subsection could be linked to. But here is a new patch. ---------- Added file: http://bugs.python.org/file26652/issue-15521-2.patch _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue15521> _______________________________________