run-tests: handle windows crlf in .py tests again

Before af7c6bc48d8d all crlf occurrences in test output on Windows were simply
changed to lf. In af7c6bc48d8d it was replaced by more clever handling in the
.t test runner ... but the .py runner was forgotten and many .py tests were
failing on Windows.

The crlf/lf replacement is now reintroduced in the py test runner.

tests/run-tests.py

@@ -476,6 +476,8 b' def pytest(test, wd, options, replacemen'
     py3kswitch = options.py3k_warnings and ' -3' or ''
     cmd = '%s%s "%s"' % (PYTHON, py3kswitch, test)
     vlog("# Running", cmd)
+    if os.name == 'nt':
+        replacements.append((r'\r\n', '\n'))
     return run(cmd, wd, options, replacements)
 
 def shtest(test, wd, options, replacements):