Don't fail if job_builder.config.path is not set

Change-Id: I7698d2726e250e38513eba7e04c1fe8ec37934b0
diff --git a/jenkins/job_builder.sls b/jenkins/job_builder.sls
index 01c5238..fe25c54 100644
--- a/jenkins/job_builder.sls
+++ b/jenkins/job_builder.sls
@@ -62,7 +62,7 @@
 
 jenkins_job_builder_jobs_update:
   cmd.run:
-  - name: jenkins-jobs update /srv/jenkins/job_builder_config/{{ job_builder.config.path }}
+  - name: jenkins-jobs update /srv/jenkins/job_builder_config/{{ job_builder.config.path|default("") }}
   - require:
     - git: {{ job_builder.config.address }}
     - file: {{ job_builder.dir.conf }}/jenkins_jobs.ini