They can only change the license of future contributions alone. Your contributions are still protected by your original license, unless you agreed to some othe

They can only change the license of future contributions alone. Your contributions are still protected by your original license, unless you agreed to some other license in parallel (such as via a contributor agreement). Therefore, by including your work without respecting the terms of your license (such as the MIT license text inclusion), they are violating your copyright. As such, any contributor agreement should make you think twice.