mvn -U does NOT update/download the latest SNAPSHOT version

• Complexity:

  Intermediate

I stumbled on this issue (again) with a new snapshot release of Apache's XMLRPC library (3.1-SNAPSHOT).
For background information see here: http://www.nabble.com/3.1-SNAPHOT-tf2411158.html

The bug is that mvn -U doesn't download the new 3.1-SNAPSHOT version when there is one. I had (actually we as in our team) manually have to delete the existing 3.1-SNAPSHOT in my local repository.
The xmlrpc library consists of three modules (common, server and client) this problems applies to all three but I've make an example using the server modules.

It can be found here: http://people.apache.org/maven-snapshot-repository/org/apache/xmlrpc/xmlrpc-server/3.1-SNAPSHOT/

The SNAPSHOTs generated does not use uniqueVersion (and filenames are hence not created with a timestamp). Is that necessary for mvn -U to work?

If that is the case then

1) this needs to be documented better. It is NOT how one expects it to work. As a user I don't care how the SNAPSHOT was deployed - just that it is there.
2) one should be able to force mvn to RE-download all SNAPSHOT (don't check for update or anything just download). perhaps mvn -F (force redownload of snapshots)