As seen on https://github.com/jenkinsci/git-plugin/pull/212, the PR status links to https://ci.jenkins.io/blue/organizations/jenkins/Plugins%2Fgit-plugin/detail/PR-212/21/pipeline, returning a 404 error code.

The real (even seemingly wrong) url is https://ci.jenkins.io/blue/organizations/jenkins%20/Plugins%2Fgit-plugin/detail/PR-212/21/pipeline/

Note the extra space (%20) after the organization name, causing the 404