Fix readline error message that should be only for win32. Closes #175

IPython/Magic.py

@@ -1,7 +1,7 b''
 # -*- coding: utf-8 -*-
 """Magic functions for InteractiveShell.
 
-$Id: Magic.py 2464 2007-06-27 23:03:07Z vivainio $"""
+$Id: Magic.py 2569 2007-07-31 19:48:00Z fperez $"""
 
 #*****************************************************************************
 #       Copyright (C) 2001 Janko Hauser <[e-mail]> and
@@ -2134,7 +2134,7 b' Currently the magic system has the following functions:\\n"""'
             print 'You must specify a color scheme.'
             return
         import IPython.rlineimpl as readline
-        if not readline.have_readline:
+        if not readline.have_readline and sys.platform == "win32":
             msg = """\
 Proper color support under MS Windows requires the pyreadline library.
 You can find it at: