run-tests: extract sorting of tests to own function
TestRunner._run() is a large function and is difficult to follow.
Let's extract the test sorting to its own function to make it shorter.
When I refactored run-tests.py several years ago, I put a lot of
functionality in methods. The prevailing Mercurial style is to use
functions - not classes - where possible. While refactoring the code,
I decided to undo this historical mistake of mine by moving the code
to a standalone function.
Differential Revision: https://phab.mercurial-scm.org/D1750
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state