The quoting works fine for cookie values, but doesn't kick in for 
attributes like Comment. 

>>> c = SimpleCookie()
>>> c['foo'] = u'\N{COPYRIGHT SIGN}'.encode('UTF8')
>>> print str(c)
Set-Cookie: foo="\302\251";
>>> c['foo']['comment'] = u'\N{BIOHAZARD SIGN}'.encode('UTF8')
>>> print str(c)
Set-Cookie: foo="\302\251"; Comment=?;
>>> str(c)
'Set-Cookie: foo="\\302\\251"; Comment=\xe2\x98\xa3;'
>>> 

This patch adds an unicode character, converted to UTF8 as a cookie's
comment and then checks if it is correctly quoted.

This patch properly quotes cookie's comment and successfully passes
test_cookie.py with applied patch.

Thanks, Zan!

All tests pass with both patches applied. Test and fix look correct to me.