run-test: make it clearer why we terminating process

The --verbose log wer only talking about process termination. Now we have more
information about why.

Differential Revision: https://phab.mercurial-scm.org/D10394

tests/run-tests.py

@@ -301,6 +301,7 b' def Popen4(cmd, wd, timeout, env=None):'
             while time.time() - start < timeout and p.returncode is None:
                 time.sleep(0.1)
             p.timeout = True
+            vlog('# Timout reached for process %d' % p.pid)
             if p.returncode is None:
                 terminate(p)