tools/webpack-jumpstart: wait to clone node_modules
tools/webpack-jumpstart: wait to clone node_modules

Move the clone of node_modules to much lower in the script, at the point
where it's actually required (ie: directly before we need to compare
package-lock.json).

mvollmer/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,cockpit-project/cockpit,martinpitt/cockpit,cockpit-project/cockpit