Broken ci-test argument parsing

--platforms x86_64-centos7-gcc9-opt should work (and not only --platforms=x86_64-centos7-gcc9-opt). Consider the following broken example:

DEBUG:LbNightlyTools.Scripts.GitlabMR:comment is
/ci-test --merge --platforms x86_64-centos7-gcc9-opt
INFO:LbNightlyTools.Scripts.GitlabMR:Found trigger with arguments Namespace(merge=True, params=[], platforms=u'lhcb/x86_64-centos7-gcc9-opt', sources=['lhcb/Rec!2232'])
DEBUG:LbNightlyTools.GitlabUtils:_getGitlabProject invoked with (('lhcb/Rec',), {})
DEBUG:LbNightlyTools.GitlabUtils:result not in cache, invoking the function
DEBUG:LbNightlyTools.GitlabUtils:_gitlabServer invoked with ((), {})
DEBUG:LbNightlyTools.GitlabUtils:result in cache
DEBUG:urllib3.connectionpool:https://gitlab.cern.ch:443 "GET //api/v4/projects/lhcb%2FRec HTTP/1.1" 200 2989
DEBUG:urllib3.connectionpool:https://gitlab.cern.ch:443 "GET //api/v4/projects/401/merge_requests/2232 HTTP/1.1" 200 3568
INFO:LbNightlyTools.Scripts.GitlabMR:json job configuration:
{
  "sources": [
    "lhcb/Rec!2232"
  ], 
  "merge": true, 
  "trigger": {
    "merge_request_iid": 2232, 
    "project_id": 401, 
    "discussion_id": "23aebfe2fd2ee90485633e906ad9a80787bff6f7", 
    "note_id": 3875543
  }, 
  "platforms": "lhcb/x86_64-centos7-gcc9-opt"
}