They wouldn't be able to copyright the design of the shirt. Even if there was I'm sure 5 points of difference could be incorporated into it, such as having the taller stripes starting on the right, maybe dark blue shirt and light blue stripes etc. the badge I don't think is copyrighted as that...
If a shirt was created which had the same design as the new shirt, but with a SISU out logo on the front and the coventry crest on the right, would supporters buy it? Should be able to get them manufactured and sold for under £10. This way fans can support the team by wearing the colours but...