Fix to allow equals in value of environment variable. Mirrors #4328

provisioner/windows-shell/provisioner.go

@@ -301,7 +301,7 @@ func (p *Provisioner) createFlattenedEnvVars() (flattened string, err error) {
 
 	// Split vars into key/value components
 	for _, envVar := range p.config.Vars {
-		keyValue := strings.Split(envVar, "=")
+		keyValue := strings.SplitN(envVar, "=", 2)
 		if len(keyValue) != 2 || keyValue[0] == "" {
 			err = errors.New(fmt.Sprintf("Shell provisioner environment variables must be in key=value format. Currently it is '%s'", envVar))
 			return