I sometimes see open source projects that want to switch their licenses to a more permissive one. If original author of a project or community around it want to switch license then they must ask all contributors for a permission to do so. For example this happens with GPL to Apache 2 conversions.
In text of Apache 2 license and Github terms of servise there is note that contributions can be under different conditions than project. As I am aware this is used in various CLA's, but requirements to sign a CLA is not a warm welcome for developers. Can contributions be simply licensed under more permissive licence instead of using CLA, just by making note in comment that this PR is under MIT?
Example: Author published library under LGPLv3. In every pull request contributors agree that their contribution is under MIT license. Author can later relicence code under MIT license without asking contributors for permission.