Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Demo/metaclasses/Meta.py b/Demo/metaclasses/Meta.py
index 39cbef6..5534074 100644
--- a/Demo/metaclasses/Meta.py
+++ b/Demo/metaclasses/Meta.py
@@ -98,7 +98,7 @@
         def __init__(self, *args):
             print "__init__, args =", args
         def m1(self, x):
-            print "m1(x=%s)" %`x`
+            print "m1(x=%r)" % (x,)
     print C
     x = C()
     print x