Log Message:
Updated py-dulwich to 0.15.0.

0.15.0	2016-10-09

 BUG FIXES

  * Allow missing trailing LF when reading service name from
    HTTP servers. (Jelmer Vernooij, Andrew Shadura, #442)

  * Fix dulwich.porcelain.pull() on Python3. (Jelmer Vernooij, #451)

  * Properly pull in tags during dulwich.porcelain.clone.
    (Jelmer Vernooij, #408)

 CHANGES

  * Changed license from "GNU General Public License, version 2.0 or later"
    to "Apache License, version 2.0 or later or GNU General Public License,
    version 2.0 or later". (#153)

 IMPROVEMENTS

  * Add ``dulwich.porcelain.ls_tree`` implementation. (Jelmer Vernooij)