Don't attempt cache updates in Docker container

Author: oliversalzburg

lib/update-cache.js

@@ -5,6 +5,11 @@ var async = require('async');
 var packageHash = require('./package-hash');
 
 function updateCache(context, projectDir, done) {
+  // We don't support any caching in a docker container, as the container is reconstructed on every run anyway.
+  if (context.runnerId === 'docker') {
+    return done();
+  }
+
   var cachier = context.cachier('modules');
 
   packageHash(projectDir, function (err, hash) {