I had to create new question, because my answers are considered bad
I am referring to this already answered question.
Kiquenet asked it already in comment to the answer, but noone answered him.
Now, when we all know why it happens, can anyone tell if (and if then how) there is any solution to the issue which does not involve rebuilding projects?
In my case where assemblies are loaded dynamically and apart from that are shared between different versions of projects it is not acceptable for me to rebuild all everytime I need new version of loaded assembly.
All interfaces are implemented correctly and option like: "indefinite reference"/"version invariant" would be perfect.
Simple solution: rebuild all assemblies.
Your requirement to avoid rebuilding projects is unreasonable. Some changes in the code do require you to rebuild projects. There's no way to avoid this, except never ever changing interfaces (and other features shared by many types).