user vita is an outdated but well-working name for user talk namespace in Hungarian Wikipedia. If I write [[user vita:Bináris]], it takes me directly to my talk page (which is now called Szerkesztővita:Bináris).
But for the code
s = u'user vita:Bináris'
p = pywikibot.Page(site,s)
print p.namespace()
the result is 0 instead of 3. Where is the error?