[session] drop useless getter and setter for security Those function have very few user and does not anything fancy. Internal user now access tx.read/write_security directly. External user have been blessed with a writable property. They are only interested in the write part of they did not used the return of the removed function. They access it through the session since I prefer the external world to not be aware of Transaction yet.

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)