Log Message:
Update to 3.20171001. From the changelog:

[ Joey Hess ]
* htmlscrubber: Add support for the video tag's loop and muted
  attributes. Those were not in the original html5 spec, but have been
  added in the whatwg html living standard and have wide browser support.
* emailauth, passwordauth: Avoid leaving cgisess_* files in the
  system temp directory.

[ Simon McVittie ]
* core: Don't decode the result of strftime if it is already tagged as
  UTF-8, as it might be since Perl >= 5.21.1. (Closes: #869240)
* img: Strip metadata from resized images when the deterministic config
  option is set. Thanks, intrigeri
* receive: Avoid asprintf() in IkiWiki::Receive, to avoid implicit
  declaration, potential misbehaviour on 64-bit platforms, and lack
  of portability to non-GNU platforms
* t: Add a regression test for untrusted git push
* receive: Fix untrusted git push with git (>= 2.11) by passing through
  the necessary environment variables to make the quarantine area work
* debian: Declare compliance with Debian Policy 4.1.1

[ Amitai Schleier ]
* l10n: Fix the build with po4a 0.52, by ensuring that msgstr ends
  with a newline if and only if msgid does