[MapProxy] error parsing tms sources with ampersand in url

[Travis Kirstine]

I recently updated to mapproxy  1.12.0a-20190605 and having issues with the
parsing of the source tms url which contain an @ which is used in
MapCache.  In the mapproxy log it appears the url path before the @ is
removed resulting in

"could not retrieve tile: No response from URL "http://gmaps/10/186/688.xxx":
Name or service not known"

## source tms
   lacombe_2015_tms:
      type: tile
      url: '
http://foobar.com/mapcache/tms/1.0.0/lacombe@gmaps/%(tms_path)s.xxx'
      grid: spherical_mercator
      transparent: true
      on_error:
         404:
            response: transparent
            cache: false
      coverage:
         datasource: "PG: dbname='db' host='db' user='db' password='db'"
         where: 'SELECT boundary_3857 FROM layer WHERE id = 314'
         srs: 'EPSG:3857'

This worked in version 1.10 and 1.11
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/mapproxy/attachments/20190610/8412e5ea/attachment.html>