Sunspot and Solr on Tomcat: Trouble with Umlauts

We experienced problems with Sunspot and Solr on Tomcat: Umlauts (ä, ö, ü) were not correctly handled on Tomcat while everything was okay on the local development machines (your local Sunspot service you start with the sunspot:solr:run task is based on Jetty).

We use a stemmer that reduces "Sänger" to "sang" and "Sanger" to "sang" as well.
Though, results for "Sänger" where empty on Tomcat.

This is due to a UTF-8 bug in RSolr (see Github Show archive.org snapshot for some discussion on that).
The bug is fixed in a new version of RSolr. Simply run bundle update rsolr. Version 1.0.6 works for us.