Npm assets are not copied to drupal folder on first composer install

[ol0lll]

After intial composer install libs are not present in docroot/libraries

$ find . -name select2*
./docroot/modules/contrib/select2
./docroot/modules/contrib/select2/config/schema/select2.schema.yml
./docroot/modules/contrib/select2/css/select2.seven-overrides.css
./docroot/modules/contrib/select2/css/select2.seven.css
./docroot/modules/contrib/select2/js/select2.js
./docroot/modules/contrib/select2/select2.info.yml
./docroot/modules/contrib/select2/select2.libraries.yml
./docroot/modules/contrib/select2/select2.module
./docroot/modules/contrib/select2/select2.routing.yml
./docroot/modules/contrib/select2/select2.services.yml
./vendor/npm-asset/select2
./vendor/npm-asset/select2/dist/css/select2.css
./vendor/npm-asset/select2/dist/css/select2.min.css
./vendor/npm-asset/select2/dist/js/select2.full.js
./vendor/npm-asset/select2/dist/js/select2.full.min.js
./vendor/npm-asset/select2/dist/js/select2.js
./vendor/npm-asset/select2/dist/js/select2.min.js
./vendor/npm-asset/select2/src/js/select2

Doing another composer install npm-assets are installed a second time:

$ composer install
Gathering patches for root package.
Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Package operations: 3 installs, 0 updates, 0 removals
Gathering patches for root package.
Gathering patches for dependencies. This might take a minute.
  - Installing npm-asset/jquery-mousewheel (3.1.13): Loading from cache
  - Installing npm-asset/almond (0.3.3): Loading from cache
  - Installing npm-asset/select2 (4.0.5): Loading from cache
Generating autoload files
> ThunderDevelop\composer\ScriptHandler::createRequiredFiles

Files are now present in docoot/libraries

$ find . -name select2*
./docroot/libraries/select2
./docroot/libraries/select2/dist/css/select2.css
./docroot/libraries/select2/dist/css/select2.min.css
./docroot/libraries/select2/dist/js/select2.full.js
./docroot/libraries/select2/dist/js/select2.full.min.js
./docroot/libraries/select2/dist/js/select2.js
./docroot/libraries/select2/dist/js/select2.min.js
./docroot/libraries/select2/src/js/select2
./docroot/modules/contrib/select2
./docroot/modules/contrib/select2/config/schema/select2.schema.yml
./docroot/modules/contrib/select2/css/select2.seven-overrides.css
./docroot/modules/contrib/select2/css/select2.seven.css
./docroot/modules/contrib/select2/js/select2.js
./docroot/modules/contrib/select2/select2.info.yml
./docroot/modules/contrib/select2/select2.libraries.yml
./docroot/modules/contrib/select2/select2.module
./docroot/modules/contrib/select2/select2.routing.yml
./docroot/modules/contrib/select2/select2.services.yml
./vendor/npm-asset/select2
./vendor/npm-asset/select2/dist/css/select2.css
./vendor/npm-asset/select2/dist/css/select2.min.css
./vendor/npm-asset/select2/dist/js/select2.full.js
./vendor/npm-asset/select2/dist/js/select2.full.min.js
./vendor/npm-asset/select2/dist/js/select2.js
./vendor/npm-asset/select2/dist/js/select2.min.js
./vendor/npm-asset/select2/src/js/select2