Artifact publishing terminates prematurely if shared artifact cannot be published

If a job has multiple artifacts, and one or more of those artifacts is a shared artifact that fails to publish, then the publishing of any remaining artifacts in that job will be skipped.

For example, say a job has artifacts A, B, and C to be published, and B is a shared artifact. At the end of the job, A is published OK, but then if if B cannot be published (e.g. if the directory can't be found), then the job will finish immediately, and C will not be published.

This is a real pain. Those later artifacts may be crucial to diagnosing the build, but we never get to see them because of the premature termination of the job.

Unpublished shared artifacts should prevent downstream jobs from running, but they should allow all artifacts in the current job to be published.