Regarding Pull Requests, this is quite important if and when you want to change licenses, or dual license.
Make sure you have on file release forms for every copyright holder who submits code that grant you permission to relicense later on. For one line bug fixes it can be a pain, but it's worth it.
One problem with this though is that it places an unfair advantage with the current maintainer. A fork of the project wouldn't inherit the relicensing permissions from all the contributors.
