I installed an update on our jenkins installation and also updated several plugins. After the update several jobs were not able to retrieve the latest release version from my maven repository. Investigating the console output showed me the mentioned exception when trying to download the maven-metadata.xml. For further details please see
I downgraded the Repository Connector Plugin to 0.8.2 an everything works again. So the bug seems to be part of the 1.0.1 release of the plugin.