Your patch will not apply on top of our git because I rebuilt it for protobuf 3.0.0 this week:

https://git.solus-project.com/packages/cockatrice/commit/?id=993443f3d15392c4b6941e21a7c89dfc68638809

Since it's just a simple tarball and version bump, I've gone ahead an updated it locally. Next time, be sure to update your local clone first. You never know when we might need to rebuild something.

Landed in unstable:

https://git.solus-project.com/packages/cockatrice/commit/?id=3f2cbf1e2d9f3256be351eb047e7e5d52db8e6b8