[PATCH] py3: add b'' to some run-tests.py strings for Windows

[Matt Harbison]

# HG changeset patch
# User Matt Harbison <matt_harbison at yahoo.com>
# Date 1536802328 14400
#      Wed Sep 12 21:32:08 2018 -0400
# Node ID dfb052baace5510876f56e67f49b082273ebb858
# Parent  2105ed5ef206052a5ff093fba8cbd44bef470f20
py3: add b'' to some run-tests.py strings for Windows

Things go seriously off the rails after this, so there may be more that are
missing.

# skip-blame since these are just converting to bytes literals

diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -3118,8 +3118,8 @@ class TestRunner(object):
     def _checktools(self):
         """Ensure tools required to run tests are present."""
         for p in self.REQUIREDTOOLS:
-            if os.name == 'nt' and not p.endswith('.exe'):
-                p += '.exe'
+            if os.name == 'nt' and not p.endswith(b'.exe'):
+                p += b'.exe'
             found = self._findprogram(p)
             if found:
                 vlog("# Found prerequisite", p, "at", found)