`cordova plugin add` does not honor npm registry defined globally

C:\Users\IGEN261\code\uit\test\6-hwc\dist\hwc\cordova-project-android>cordova plugin add private-plugin@2.0.5 -d
No scripts found for hook "before_plugin_add".
Calling plugman.fetch on plugin "private-plugin@2.0.5"
Fetching plugin "private-plugin@2.0.5" via npm
Error: CordovaError: Failed to fetch plugin private-plugin@2.0.5 via registry.
Probably this is either a connection problem, or plugin spec is incorrect.
Check your connection and plugin name/version/URL.
Error: Registry returned 404 for GET on https://registry.npmjs.org/private-plugin
    at C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\cordova-lib\src\plugman\fetch.js:192:33
    at _rejected (C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\q\q.js:797:24)
    at C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\q\q.js:823:30
    at Promise.when (C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\q\q.js:1035:31)
    at Promise.promise.promiseDispatch (C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\q\q.js:741:41)
    at C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\q\q.js:557:44
    at flush (C:\Users\IGEN261\AppData\Roaming\npm\node_modules\cordova\node_modules\q\q.js:108:17)
    at doNTCallback0 (node.js:430:9)
    at process._tickCallback (node.js:359:13)

>npm config list
; cli configs
long = true
user-agent = "npm/3.3.12 node/v5.1.0 win32 x64"

; userconfig C:\Users\IGEN261\.npmrc
progress = true

; builtin config undefined
registry = "http://privaterepo.com"