Before this commit, when duplicating a task,
the pad of the original one was updated with plain text
Hence losing all the layout.
This was because, in all likelihood, Odoo's Etherpad server did not support pushing HTML
At the time of the commit, Odoo's pads can receive HTML.
We then push HTML by default, falling back to pushing text as before
if necessary
OPW 806064
In Python 3, all of these were "consolidated" under urllib(.request,
.parse, .errors) which is inconvenient.
Since we already have hard dependencies on requests and
werkzeug(.urls, which is a backport of Python 3's unicode-aware
urllib.parse) migrate *everything* to that.
A sticking point is urllib2.URLError, those were (mostly) replaced by
the slightly more general IOError which URLError extends.
Christophe Simonis