Issue #20270: urllib and urlparse now support empty ports.
diff --git a/Lib/urllib.py b/Lib/urllib.py
index 244cb05..ac5d797 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1125,10 +1125,13 @@
     global _portprog
     if _portprog is None:
         import re
-        _portprog = re.compile('^(.*):([0-9]+)$')
+        _portprog = re.compile('^(.*):([0-9]*)$')
 
     match = _portprog.match(host)
-    if match: return match.group(1, 2)
+    if match:
+        host, port = match.groups()
+        if port:
+            return host, port
     return host, None
 
 _nportprog = None
@@ -1145,12 +1148,12 @@
     match = _nportprog.match(host)
     if match:
         host, port = match.group(1, 2)
-        try:
-            if not port: raise ValueError, "no digits"
-            nport = int(port)
-        except ValueError:
-            nport = None
-        return host, nport
+        if port:
+            try:
+                nport = int(port)
+            except ValueError:
+                nport = None
+            return host, nport
     return host, defport
 
 _queryprog = None