npm/npm — pull request #6267 by timoxley (2014-09-22 18:00:54+00:00)
Title: Skip installation of installed scoped packages.

Currently scoped packages will be reinstalled regardless if they already exist in the node_modules tree.

This makes scoped packages skip reinstallation the same way normal, unscoped packages do.

e.g.

#### `package.json`
```json
{
"name": "scopedinstall",
"version": "1.0.0",
"dependencies": {
"@fruit/apple": "file:apple",
"cashew": "file:cashew"
}
```

#### `./apple/package.json`

```json
{
"name": "@fruit/apple",
"version": "1.0.0"
}
```
#### `./cashew/package.json`

```json
{
"name": "cashew",
"version": "1.0.0"
}
```

## Before

Note `cashew` is only installed once, `@fruit/apple` is reinstalled every `npm install`.

```
> npm install --loglevel=silent
cashew@1.0.0 node_modules/cashew

@fruit/apple@1.0.0 node_modules/@fruit/apple

> npm install --loglevel=silent
@fruit/apple@1.0.0 node_modules/@fruit/apple

> npm install --loglevel=silent
@fruit/apple@1.0.0 node_modules/@fruit/apple
```

## After
Note npm has ceased reinstalling `@fruit/apple` every `npm install`.

```
> npm install --loglevel=silent
cashew@1.0.0 node_modules/cashew

@fruit/apple@1.0.0 node_modules/@fruit/apple
> npm install --loglevel=silent

> npm install --loglevel=silent

```