Unity 4.5: Where's the Preferences → Packages-menu gone?

I'm researching on best practises on setting up and using GIT, when working in Unity. I participate in a lot of projects that could benefit from getting it right (in every detail).

In my search, I encounter the following statement a few times:

Enable External option in Unity → Preferences → Packages → Repository

(e.g. here: http://stackoverflow.com/questions/21573405/how-to-prepare-a-unity-project-for-git )

It seems like a rather important step. I've found the option in Unity 4.3, but in Unity 4.5 the Packages-menu seems to be gone from Preferences.

1) Can anyone confirm, that this is the case?

2) What did it exactly do? (why was it an important setting regarding version control?)

3) Where is it now? (Should I do something else to make a similar change?)

Please help me if you know anything about this issue. This is very important to me!