Updating invalid bundle error message to be clearer about forks without enough watchers

                    
|Q            |A   |
|---          |--- |
|Bug Fix?     |n   |
|New Feature? |n   |
|BC Breaks?   |n   |
|Deprecations?|n   |
|Tests Pass?  |y   |
|Fixed Tickets|#302|
|License      |MIT |
|Doc PR       |    |
                    


 Sent using [Gush](https://github.com/gushphp/gush)