Application broken after upgrading from v4.03 to v4.0.4

This is a breaking change

SRY, slightly OT:
(Being new to CI) While it’s always a good idea to read the change log, are breaking changes to be expected for bugfix releases?
Or doesn’t CI use SemVer and the version number only looks like it?

As the author of this fix I'd like to chime in with a question to this:

My first attempt of fixing this was by adding an additional interface FilterInterfaceWithArguments since I didn't like the idea of messing with interfaces and breaking existing code. Adding a new interface had the pros of not breaking existing code, but the cons of adding complexity to the framework with basically this interfaces for the same thing, but one interface working as described in the docs. 
By fixing the bug this way the framework was kept clean and the bug was fixed.

So, my question: since SemVer §8 states that "Major version X (X.y.z | X > 0) MUST be incremented if any backwards incompatible changes are introduced to the public API."
should the fix either have been
a) a new interface or
b) a release of CI 5.0.0?

As a side note I'd like to see the re-introduction of the minor upgrade docs from CI3.

/Mattias