Sometimes I want to be able to block the execution of the current build until the completion of the remote build. In this case, I also want to decide whether the current build should be marked as failed in case the remote build failed or if it should just ignore it and continue.

Hint: the async-http-client is a shared lib plugin which might help you to implement this: https://wiki.jenkins-ci.org/display/JENKINS/Async+Http+Client+Plugin