ignore empty

shadowsocks/common.py

@@ -297,6 +297,7 @@ class PortRange(object):
             try:
                 int_range = item.split('-')
                 if len(int_range) == 1:
+                    if item:
                         self.range.add(int(item))
                 elif len(int_range) == 2:
                     int_range[0] = int(int_range[0])