clean up workspace before starting

Change-Id: I6cce25b3634a5a631f0530a89466d0ba5f3f6195
diff --git a/jobs.yaml b/jobs.yaml
index 04dd03c..3322621 100644
--- a/jobs.yaml
+++ b/jobs.yaml
@@ -3,13 +3,17 @@
     project-type: freestyle
     description: |
         This is an auto-generated job.
-        
+
         To add or modify a job, look for the "vm-build" project on https://gerrit.onlab.us
     logrotate:
         daysToKeep: 3
         numToKeep: 3
         artifactDaysToKeep: -1
         artifactNumToKeep: -1
+    wrappers:
+      - workspace-cleanup:
+          - include: "*"
+          dirmatch: true
 
 # ---- Mininet Build and Test Jobs ----
 - project:
@@ -69,6 +73,9 @@
         This job updates Jenkins jobs automatically when updates are make to the YAML file.
 
         To add or modify a job, look for the "vm-build" project on https://gerrit.onlab.us
+    wrappers:
+      - workspace-cleanup:
+          - exclude: "*"
     scm:
       - git:
           url: ssh://jenkins@gerrit.onlab.us:29418/vm-build
@@ -95,6 +102,9 @@
     name: update-jenkins-verify
     description: |
         This job is used to verify new Jenkins jobs using jenkins-job test before they are accepted in Gerrit.
+    wrappers:
+      - workspace-cleanup:
+          - exclude: "*"
     scm:
       - git:
           url: ssh://jenkins@gerrit.onlab.us:29418/vm-build