py3: don't index into bytes in phabricator's _tokenize()
`phabread`ing a stack using `hg phabread :D1234` under py3 will currently die
with a KeyError because it will index into `b':D1234'` and return `58` instead
of `b':'` as a token.
Differential Revision: https://phab.mercurial-scm.org/D7129
pager.pager=p0 # $TESTTMP/sysrc:4
ui.editor=e1 # $TESTTMP/userrc:2
pager.pager=p2 # $PAGER
ui.editor=e1 # $TESTTMP/userrc:2