npm tags vs github urls

Following discussion from https://github.com/visionmedia/npm/pull/15 .

If you write this to your package.json:

```js
  "dependencies": {
    "github-package":"visionmedia/commander.js"
  },
```

npm will always request "github-package" from registry assuming that "visionmedia/commander.js" is a tag.

If this tag doesn't exist, npm will try to fetch it from github as a fallback.

My point is: since "user/repo" is an invalid tag (you can't do "npm tag package@1.2.3 user/repo"), I suggest it to make github request without hitting registry at all.