Directly calling a subsidiary formula that will be using the git download strategy requires that the name be passed manually:  https://github.com/mxcl/homebrew/blob/master/Library/Homebrew/download_strategy.rb#L332-342

Otherwise you get:

```
$ brew install --HEAD glulxe
==> Cloning https://github.com/erkyrath/glulxe.git
Updating /Library/Caches/Homebrew/glulxe--git
Error: strategy requires a name parameter
Please report this bug:
    https://github.com/mxcl/homebrew/wiki/troubleshooting
/usr/local/Library/Homebrew/download_strategy.rb:332:in `initialize'
[...]
```

This is also the case, it appears, for other VCS download strategies, but not for curl: https://github.com/mxcl/homebrew/blob/master/Library/Homebrew/download_strategy.rb#L40-48