[predicates] keep making `yes` predicate importable from cubicweb (closes #2790319)
The `yes` predicate was moved out in CubicWeb 3.15 but it should have
remained importable from the cubicweb.predicates module, for bw compat
reasons and also because logilab.common.registry is an implementation
detail.
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)