[source/native] fix sqlserver pattern matcher for unique constraints (closes #3227593)
The matcher is used to parse the low-level error message and extract
meaningful information for the end users.
If broken, the users see an alarming and bewildering message.
A full & definitive fix is scheduled for CubicWeb 3.18.
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)