encoding problem

[digisatori at gmail.com]

The below snippet code generates UnicodeDecodeError.
#!/usr/bin/env python
#--*-- coding: utf-8 --*--
s = 'äöü'
u = unicode(s)


It seems that the system use the default encoding- ASCII to decode the
utf8 encoded string literal, and thus generates the error.

The question is why the Python interpreter use the default encoding
instead of "utf-8", which I explicitly declared in the source.