Log Message:
Update to 3.20161229. From the changelog:

* Security: force CGI::FormBuilder->field to scalar context where
  necessary, avoiding unintended function argument injection
  analogous to CVE-2014-1572. In ikiwiki this could be used to
  forge commit metadata, but thankfully nothing more serious.
  (CVE-2016-9646)
* Security: try revert operations in a temporary working tree before
  approving them. Previously, automatic rename detection could result in
  a revert writing outside the wiki srcdir or altering a file that the
  reverting user should not be able to alter, an authorization bypass.
  (CVE-2016-10026 represents the original vulnerability.)
  The incomplete fix released in 3.20161219 was not effective for git
  versions prior to 2.8.0rc0.
  (CVE-2016-9645 represents that incomplete solution.)
* Add CVE references for CVE-2016-10026
* Add automated test for using the CGI with git, including
  CVE-2016-10026
  - Build-depend on libipc-run-perl for better build-time test coverage
* Add missing ikiwiki.setup for the manual test for CVE-2016-10026
* git: don't issue a warning if the rcsinfo CGI parameter is undefined
* git: do not fail to commit changes with a recent git version
  and an anonymous committer