Convert hash.digest() to unicode

import hashlib
string1 = u'test'
hashstring = hashlib.md5()
hashstring.update(string1)
string2 = hashstring.digest()

unicode(string2)

UnicodeDecodeError: 'ascii' codec can't decode byte 0x8f in position 1: ordinal
not in range(128)

The string HAS to be unicode for it to be any use to me, can this be done? Using python 2.7 if that helps...