Merge branch 'to-2.30.1' into 'master'

To 2.30.1

See merge request !2
20 jobs for release/2.30.1-1 in 2 minutes and 1 second (queued for 1 second)
latest
Name Stage Failure
failed
docker_build Build
$ deployer build \ # collapsed multi-line command
importing image...skipped. "image.tar.gz" not found
building image...adding HTTP_PROXY=http://proxy.uni-leipzig.de:3128 to build command
adding HTTPS_PROXY=http://proxy.uni-leipzig.de:3128 to build command
adding NO_PROXY=docker,localhost,127.0.0.1,.uni-leipzig.de,172.18.85.125 to build command
failed
time="2019-07-24T14:29:56Z" level=error msg="failed to dial gRPC: cannot connect to the Docker daemon. Is 'docker daemon' running on this host?: dial tcp 172.17.0.2:2375: connect: connection refused"
context canceled
ERROR: Job failed: exit code 1