Remove deprecated U option to open on python 3.

[Issue #252]

diff --git a/dns/zone.py b/dns/zone.py
index 37f23d3d362f247cc5a7ef4622b5edaa40434010..6606bef0e314d7a7064d530113fb1aa0d6de41bf 100644 (file)
--- a/dns/zone.py
+++ b/dns/zone.py
@@ -1021,7 +1021,10 @@ def from_file(f, origin=None, rdclass=dns.rdataclass.IN,
     """
 
     str_type = string_types
-    opts = 'rU'
+    if PY3:
+        opts = 'rU'
+    else:
+        opts = 'r'
 
     if isinstance(f, str_type):
         if filename is None: