soledad_sync.py doesn't terminate sometimes

I just found those two stale soledad_sync.py procs a few days old:

root@dev1:/etc/x509/certs#  ps aux|grep soled
soledad   7974  0.8  1.8 1008424 73292 ?       Sl   13:52   0:18 /usr/bin/python /usr/bin/twistd --uid=soledad --gid=soledad --pidfile=/var/run/soledad.pid --syslog --prefix=soledad-server web --wsgi=leap.soledad.server.application --port=ssl:2323:privateKey=/etc/x509/keys/leap.key:certKey=/etc/x509/certs/leap.crt:sslmethod=SSLv23_METHOD
root     29317  0.0  0.0   4332   676 ?        S    Oct02   0:00 sh -c /srv/leap/tests/server-tests/helpers/soledad_sync.py b1469efbacbb2a3dfc81715844749d0d cN_UJb2IlS4-0bP8RDMVNblUT0IR0EkH2DtVcbKwMas https://dev1.dev.pixelated-project.org:2323/user-b1469efbacbb2a3dfc81715844749d0d /usr/local/share/ca-certificates/leap_ca.crt password_xmWnAUbCQX5tuA 2>&1
root     29318  0.0  0.2 765468 10436 ?        SLl  Oct02   0:01 python /srv/leap/tests/server-tests/helpers/soledad_sync.py b1469efbacbb2a3dfc81715844749d0d cN_UJb2IlS4-0bP8RDMVNblUT0IR0EkH2DtVcbKwMas https://dev1.dev.pixelated-project.org:2323/user-b1469efbacbb2a3dfc81715844749d0d /usr/local/share/ca-certificates/leap_ca.crt password_xmWnAUbCQX5tuA

(from redmine: created on 2016-10-12, closed on 2016-11-22, duplicates #8590)