Unable to handle local plugins properly

1) create a new cordova project

2) inside the project directory, create folder "localplugins/testplugin" containing the file:

• package.json

  {
  	"name": "com.example.cordova.plugin",
  	"version": "1.0.0"
  }
  

• plugin.xml

  <?xml version="1.0" encoding="UTF-8"?>
  <plugin xmlns="http://apache.org/cordova/ns/plugins/1.0" id="com.example.cordova.plugin" version="1.0.0">
      <name>Test Plugin</name>
      <platform name="android">
          <config-file target="AndroidManifest.xml" parent="/*">
              <uses-permission android:name="android.permission.WAKE_LOCK" />
          </config-file>
      </platform>
  </plugin>
  

3) add android patform: cordova platform add android

4) prepare android: cordova prepare android

At this point, both package.json and config.xml contain a reference to the plugin using "file:localplugins/testplugin". The problem is that it's impossible to use the same plugin reference in both files, and still having plugin restoration and/or "npm install" to work.

If I delete platforms/ and plugins/ subdir (these are typically not under git revision control) and run "cordova prepare android" to restore the platforms and the plugins, it fails with error:

Discovered plugin "com.example.cordova.plugin" in config.xml. Adding it to the project
Failed to restore plugin "com.example.cordova.plugin" from config.xml. You might need to try adding it again. Error: Failed to fetch plugin file:localplugins/testplugin via registry.
Probably this is either a connection problem, or plugin spec is incorrect.
Check your connection and plugin name/version/URL.
Failed to get absolute path to installed module

If I edit package.json and config.xml, and remove the prefix "file:" in the plugin spec, then restoration works ok. But then, it's "npm install" that fails.

What works is to use the "file:" prefix in package.json and not use it in "config.xml". But that's not possible as preparation will make sure both are identical.