NMML/R-User-Meetings — comment on commit 966dd5ebc203514f004a32410a71aad5a25ed410
File:  line 0
By yihui:

To be honest, I just had the same problem in the past when I started using GIT, and my repository grew to tens of megabytes. I felt quite uncomfortable with that, so I googled for a while and got this hackish solution. If you are the only one who maintains this repository, this trick is fine, but if there are other people collaborating with you, this will bring a little bit trouble to them when they update their local repositories.