I think Plugin Manager already does this normally, but might fail to do so if the new version of the dependency is not yet available. Should treat that as an error condition and forbid the original plugin from being updated.

A similar problem is also when a dependency has a core version newer than the one you are using. The Plugin Manager will always download the latest version of a dependency even though its not compatible with your core version.

@rsandell: true but at least in that case there is a warning displayed in the updates screen. And since the standard Jenkins update center does not serve different content according to the version query parameter, it will be quite common for the latest version of a plugin to be newer than your current core, and you would have no way to get any update of the plugin, even if there are intermediate versions which are compatible with your core.

This already happens, so what is this issue for?

See my first comment: if the dependency update is missing, Jenkins silently ignores it.

Right. Should be fairly rare at least.