Buildout failing to pull from Git during deployments

I'm using Buildout and Mr.Developer in order to set up my environment (both for development and deployments). Part of this set up is pulling a private git repository that is required for this project. (This is why I'm using Mr.Developer.)

Most of the time when I run buildout, everything is fine.

However, after outputting the line below, it will occasionally stop. It doesn't time out or anything, but it hangs here indefinitely:

mr.developer: Queued 'django-myotherproject' for checkout.

On a normal/successful buildout, it would have outputted:

mr.developer: Queued 'django-myotherproject' for checkout.
mr.developer: Cloned 'django-myotherproject' with git.
Develop: '/projects/myproject/develop/django-myotherproject'

My initial thoughts:

I assumed that it was my git repository host that was possibly timing out (which I had hosted on webfaction). However, I just switched to github, and I'm still experiencing this issue.

Since this only occurs randomly, I don't think it's an issue of the settings I've specified in my buildout configuration file.

Update:

I increased the verbosity, and here is the output:

bin/buildout -v -v -v -c stage.cfg
Installing 'mr.developer'.
We have the best distribution that satisfies 'mr.developer'.
Picked: mr.developer = 1.20
Creating missing sources dir /projects/myproject/develop.
mr.developer: Queued 'django-myotherproject' for checkout.