[ldap] simplify connection handling
since we deleted ldapuser source, we don't need anymore the get_connection and
ConnectionWrapper stuff (that was used to put the ldap connection into the cnxset).
Also, we should simply let connection errors propagate so this is properly reported
to import logs.
from logilab.common.shellutils import generate_password
from cubicweb.server.utils import crypt_password
for user in rql('CWUser U WHERE U cw_source S, S name "system", U upassword P, U login L').entities():
salt = user.upassword.getvalue()
if crypt_password('', salt) == salt:
passwd = generate_password()
print 'setting random password for user %s' % user.login
user.set_attributes(upassword=passwd)
commit()