Merge pull request #13742 from edx/benp/npm-cache-fix

Fix for spurious 'cb() never called' errors.

scripts/jenkins-common.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+set -e
+
 source $HOME/jenkins_env
 
 # Clear the mongo database
@@ -24,3 +26,8 @@ source $HOME/edx-venv/bin/activate
 
 # add the node_js packages dir to PATH
 PATH=$PATH:node_modules/.bin
+
+# Manage the npm cache on Jenkins.
+# (In this case, remove it. That ensures from run-to-run, it is a clean npm environment)
+echo "--> Cleaning npm cache"
+npm cache clean