tests: drop unittest2 Mixed using unittest2.SkipTest and unittest.TestCase will cause skips result in errors. We are probably not going to rewriting every "unittest.TestCase" to "unittest2.TestCase", then unittest2 is causing more trouble with little benefit. Let's drop it. To remain support for Py 26 in run.py, a simple loader.discover is added.

#!/bin/sh
. $(dirname $0)/common.sh

for b in `hg branches -aq` ; do
    hg co $b || break
    echo verifying $b
    hg svn verify
done