lxc-create has been failing to download the image today with
```
+ sudo lxc-create -n buster-amd64 -t download -- -d debian -r buster -a amd64
Setting up the GPG keyring
ERROR: Unable to fetch GPG key from keyserver
lxc-create: buster-amd64: lxccontainer.c: create_run_template: 1617 Failed to create container from template
lxc-create: buster-amd64: tools/lxc_create.c: main: 327 Failed to create container buster-amd64
```
Let's try another keyserver.
Debian unstable is frozen for the Debian 9 release, current development
happens in experimental. After the release, this can be switched back to
master, and the branch set through the `$BRANCH` env variable in the
semaphore config.
This makes the default build much quicker. If people are building systemd for
packaging or actual installation, they probably need to set some more options
anyway (-Ddns-servers=, -Dntp-servers=), so adding -Dman=true is not a big
burden.
For CIs configured locally, -Dman=true is added to restore status quo ante.
Lennart Poettering