thanks Jesse Glick! apparently defining a mirror like this will make the archetype not to resolve the archetypes anymore:
<mirror> <id>repo.jenkins-ci.org-all</id> <url>http://repo.jenkins-ci.org/public</url> <mirrorOf>*</mirrorOf> </mirror>
not sure, but it might be related to the repository index information which can't be retrieved anymore (or not complete)
Not sure offhand. If you can reproduce the issue in a container environment, please file a PR against the usage instructions noting the trigger conditions, and offering a workaround if you can find one.
BTW use https protocol!
placed a PR: https://github.com/jenkinsci/archetypes/pull/42