Error: RPC failed; HTTP 500

Since today, when I want to push to my repository to gitlab.com:

Running with gitlab-runner 10.6.0-rc1 (0a9d5de9) 
on docker-auto-scale 4e4528ca 
Using Docker executor with image clojure:lein ... 
Pulling docker image clojure:lein ... 
Using docker image sha256:559adf8b1512dcf2f2ad0ed5ff87074882e8628011ab6ea4784ba43b72b35da9 for clojure:lein ... 
Running on runner-4e4528ca-project-3661804-concurrent-0 via runner-4e4528ca-srm-1521658436-f770552c... 
Cloning repository... 
Cloning into '[...]'... 
error: RPC failed; HTTP 500 curl 22 The requested URL returned error: 500 Internal Server Error 
fatal: The remote end hung up unexpectedly 
ERROR: Job failed: exit code 1 

It all worked fine before. Not sure what exactly changed, except some parts of my code, which has nothing to do with fetching/cloning a repo, does it? :). The last pipeline that did succeeded:

Running with gitlab-runner 10.6.0-rc1 (0a9d5de9)
  on docker-auto-scale fa6cab46
Using Docker executor with image clojure:lein ...
Pulling docker image clojure:lein ...
Using docker image sha256:559adf8b1512dcf2f2ad0ed5ff87074882e8628011ab6ea4784ba43b72b35da9 for clojure:lein ...
Running on runner-fa6cab46-project-3661804-concurrent-0 via runner-fa6cab46-srm-1521627920-d1a9e6f8...
Cloning repository...
Cloning into '[...]'...
Checking out 330b7ca8 as master...
Skipping Git submodules setup
[...]

What is going wrong? Why can’t the CI runner fetch the repo?

This could be related to https://gitlab.com/gitlab-com/infrastructure/issues/3909#note_64513266. If you keep seeing the failure, please comment in the thread.