Allow cloning from one branch to another

Some customers want to simply synchronize a branch to another.
For example, they work on branch ABC, deploy ABC application to production and then want to have the master branch reflect the content of the ABC branch.

This is currently not possible and ends up with an error message saying this is simply not possible.

Workaround: create a temporary project, clone the branch to it, then clone back the branch to the initial project. (that is actually tedious)