Looks like the Golang project finally realized that the Apache 2.0 license is superior to the BSD license they used because they have explicitly granted patent rights (as Apache 2.0 already does) by adding yet another file to the release source repos.
Here’s the full text for reference:
Additional IP Rights Grant (Patents)
“This implementation” means the copyrightable works distributed by Google as part of the Go project.
Google hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, transfer and otherwise run, modify and propagate the contents of this implementation of Go, where such license applies only to those patent claims, both currently owned or controlled by Google and acquired in the future, licensable by Google that are necessarily infringed by this implementation of Go. This grant does not include claims that would be infringed only as a consequence of further modification of this implementation. If you or your agent or exclusive licensee institute or order or agree to the institution of patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that this implementation of Go or any code incorporated within this implementation of Go constitutes direct or contributory patent infringement, or inducement of patent infringement, then any patent rights granted to you under this License for this implementation of Go shall terminate as of the date such litigation is filed.