Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Demo/pdist/RCSProxy.py b/Demo/pdist/RCSProxy.py
index 7212ca6..87c65cc 100755
--- a/Demo/pdist/RCSProxy.py
+++ b/Demo/pdist/RCSProxy.py
@@ -188,7 +188,7 @@
         if callable(attr):
             print apply(attr, tuple(sys.argv[2:]))
         else:
-            print `attr`
+            print repr(attr)
     else:
         print "%s: no such attribute" % what
         sys.exit(2)