#27364: fix "incorrect" uses of escape character in the stdlib.

And most of the tools.

Patch by Emanual Barry, reviewed by me, Serhiy Storchaka, and
Martin Panter.
diff --git a/Tools/scripts/pathfix.py b/Tools/scripts/pathfix.py
index 22432d1..562bbc7 100755
--- a/Tools/scripts/pathfix.py
+++ b/Tools/scripts/pathfix.py
@@ -64,7 +64,7 @@
             if fix(arg): bad = 1
     sys.exit(bad)
 
-ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')
+ispythonprog = re.compile(r'^[a-zA-Z0-9_]+\.py$')
 def ispython(name):
     return bool(ispythonprog.match(name))