Traffic Switch fails: adding again 50% to new stack

[Jan-M]

I went from, 100 / 0 to 50 / 50, which worked first time.

Then went to 100 / 0 again, then on setting 50/50 again (still the same two stacks) it fails.

➜  ~ senza traffic data-service cd75c2 50 --region eu-central-1
Calculating new weights.. OK
Stack Name  │Version│Identifier         │Old Weight%│Delta│Compensation│New Weight%│Current
data-service cd75c1  data-service-cd75c1       100.0 -50.0                     50.0         
data-service cd75c2  data-service-cd75c2         0.0  50.0                     50.0 <       
Setting weights for data-service.zmon.zalan.do...Unknown Error: type object 'ELB' has no attribute 'get_hosted_zone_for'.
Please create an issue with the content of /tmp/senza-traceback-pyz_4zi2

➜  ~ cat /tmp/senza-traceback-wtarxcg6
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/senza/error_handling.py", line 70, in __call__
    self.function(*args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 716, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 696, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 1060, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 889, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 534, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/senza/cli.py", line 1054, in traffic
    change_version_traffic(ref, percentage, region)
  File "/usr/local/lib/python3.5/dist-packages/senza/traffic.py", line 390, in change_version_traffic
    set_new_weights(version.dns_name, identifier, version.lb_dns_name, new_record_weights, percentage)
  File "/usr/local/lib/python3.5/dist-packages/senza/traffic.py", line 148, in set_new_weights
    elb_hosted_zone = ELB.get_hosted_zone_for(dns_name=lb_dns_name[idx])
AttributeError: type object 'ELB' has no attribute 'get_hosted_zone_for'