handle case when trigger is none

In case when job template contains such trigger definition:

            trigger:
              github:
              pollscm:
                spec: ${_param:jenkins_pollscm_spec}

github trigger is none, but salt formulas is written so it should handle this in [1]

[1] https://gerrit.mcp.mirantis.com/gitweb?p=salt-formulas/jenkins.git;a=blob;f=jenkins/files/jobs/_common.xml;h=8b05e640f0a122d0083675df1071df5467bd21be;hb=refs/heads/master#l39

Change-Id: I3acdf6392d4349121677845fb5f6640ba760d9ae
1 file changed