commandserver: clean up use of two-argument raise

This makes any attempt to port to Python 3 harder, and the new syntax
is supported in 2.4 already.

mercurial/commandserver.py

@@ -42,7 +42,7 b' class channeledoutput(object):'
 
     def __getattr__(self, attr):
         if attr in ('isatty', 'fileno'):
-            raise AttributeError, attr
+            raise AttributeError(attr)
         return getattr(self.in_, attr)
 
 class channeledinput(object):
@@ -122,7 +122,7 b' class channeledinput(object):'
 
     def __getattr__(self, attr):
         if attr in ('isatty', 'fileno'):
-            raise AttributeError, attr
+            raise AttributeError(attr)
         return getattr(self.in_, attr)
 
 class server(object):