Ensure clean snap

Issues a snapcraft clean to make sure there is nothing
left from any prior runs of the build.

Change-Id: I42109d8b4a750c0a4732afcf127cc407e6956ec9
Signed-off-by: beierlm <mark.beierl@canonical.com>
diff --git a/jenkins/ci-pipelines/ci_stage_2.groovy b/jenkins/ci-pipelines/ci_stage_2.groovy
index aa9c906..5cad17b 100644
--- a/jenkins/ci-pipelines/ci_stage_2.groovy
+++ b/jenkins/ci-pipelines/ci_stage_2.groovy
@@ -83,6 +83,7 @@
         stage('Snap build') {
             sh "docker pull snapcore/snapcraft:stable"
             sh "sudo rm -rf ${WORKSPACE}/stage/ ${WORKSPACE}/parts/ ${WORKSPACE}/prime/ ${WORKSPACE}/*.snap"
+            sh "sudo snapcraft clean --use-lxd"
             sh "snapcraft --use-lxd"
             sh "mv ${WORKSPACE}/${mdg}_*.snap ${WORKSPACE}/${mdg}.snap"
             sh "sudo rm -rf ${WORKSPACE}/stage/ ${WORKSPACE}/parts/ ${WORKSPACE}/prime/"