Remove Ubuntu as dependency for reproducible builds
When building TorBrowserBundle 3.x with Gitian one has to use Ubuntu. (Though not even here I succeed as I tried weeks ago, caught in a loop over and over again)
You are not building under Windows, where it would be complicated to migrate away from, this requires Ubunutu, which is based on Debian so it might work with Debian as well. If there are requirements in software that can't be shipped with Debian there are others based on that, like Linux Mint.
In fact I think this process should be agnostic to the underlying Linux distributions as long as all requirements are meet. The free choice of a distribution, even if it is just for building and even if it is just in a virtual machine, is much more important than having an unnecessary dependency. A single-point of failure.