Log Message:
Updated py-dulwich to 0.17.2.

0.17.2	2017-03-19

 BUG FIXES

 * Add workaround for
   https://bitbucket.org/pypy/pypy/issues/2499/cpyext-pystring_asstring-doesnt-work,
   fixing Dulwich when used with C extensions on pypy < 5.6. (Victor Stinner)

 * Properly quote config values with a '#' character in them.
   (Jelmer Vernooij, #511)