How to: Manual Upgrade
For manual upgrade with `git` (requires git v1.7.10+):

1. change to the `$NVM_DIR`
1. pull down the latest changes
1. check out the latest version
1. activate the new version

```sh
(
  cd "$NVM_DIR"
  git fetch --tags origin
  git checkout `git describe --abbrev=0 --tags --match "v[0-9]*" $(git rev-list --tags --max-count=1)`
) && \. "$NVM_DIR/nvm.sh"
```