spy: rename parameter dev -> file
diff --git a/serial/urlhandler/protocol_spy.py b/serial/urlhandler/protocol_spy.py
index d6ed458..c06d9c0 100644
--- a/serial/urlhandler/protocol_spy.py
+++ b/serial/urlhandler/protocol_spy.py
@@ -167,7 +167,7 @@
         output = sys.stderr
         try:
             for option, values in urlparse.parse_qs(parts.query, True).items():
-                if option == 'dev':
+                if option == 'file':
                     output = open(values[0], 'w')
                 elif option == 'color':
                     color = True