Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Tools/scripts/byteyears.py b/Tools/scripts/byteyears.py
index 9c2a974..b2a114f 100755
--- a/Tools/scripts/byteyears.py
+++ b/Tools/scripts/byteyears.py
@@ -42,7 +42,7 @@
     try:
         st = statfunc(filename)
     except os.error, msg:
-        sys.stderr.write('can\'t stat ' + `filename` + ': ' + `msg` + '\n')
+        sys.stderr.write("can't stat %r: %r\n" % (filename, msg))
         status = 1
         st = ()
     if st: