The default plugin installation strategy performs dependency resolution on its own and upload plugins. Except for the maintenance cost and fragileness, latest Jenkins versions started to overwrite plugins controlled explicitly.

The upload approach allows users to specify version or binary of the plugin to install. That is used instead of latest release available and installed. However, when the deploy of such plugin fails (which is ok as we detect that and restart) but installation of dependent plugin can cause different version of dependency to overrwrite the requested one.

Actual example: test require openstack-cloud, that depends on config-file-provider that depend on bundled plugin. When running the tests I overwrite config-file-provider version. But since that needs bundled plugin updated (which require restart) it is not dynamically deployed until restart. When openstack-cloud is being uploaded, Jenkins detects its dependency is not loaded (only installed) and fetch latest version from update center. So my attempt to override the version is ignored silently. There is no log from core or ath indicating this is happening - just .bak file in plugins dir.