[multi-sources-removal] Drop pyrorql and zmqrql sources After a few years experementing "true" multi-sources, we're now moving to "copy-based" source à la datafeed. As pyro and zmq sources have no more known customers and the related code is in the way of future refactoring of cubicweb's core, we decided to drop support for those sources without backward compatibility. If you're still using a zmqrql or pyrorql source and you want to upgrade, ask support to move it to datafeed using a pre-3.19 version first. Related to #2919300 (first step)

try:
    rtype, = __args__
except ValueError:
    print 'USAGE: cubicweb-ctl shell <instance> detect_cycle.py -- <relation type>'
    print

graph = {}
for fromeid, toeid in rql('Any X,Y WHERE X %s Y' % rtype):
    graph.setdefault(fromeid, []).append(toeid)

from logilab.common.graph import get_cycles

for cycle in get_cycles(graph):
    print 'cycle', '->'.join(str(n) for n in cycle)