[views/primary] some inner sections should use the `limit` by default to avoid a denial of service (closes #2719110) Today, it is possible to call .related and get a huge unlimited database-dos-inducing resultset that will be nevertheless limited a bit further in pure python in the `autolimited` view. While we cannot completely avoid potential denial of services such as these we mitigate the problem with the default ui settings: if the inner vid is `autolimited`, then the relation result sets is computed using the user-defined limit. This change respects the semantics of the `autolimited` view and shouldn't break anything.

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)