narrowbundle2: more kwargs native string fixes
This gets test-narrow.t to *almost* pass. Something appears to be
borked in producing bundles, but only some of the time? I'm lost, but
this change is at least a clear improvement.
# skip-blame just more r prefixes on strings
Differential Revision: https://phab.mercurial-scm.org/D2389
#require docutils gettext
$ $TESTDIR/check-gendoc it
checking for parse errors