Classloader problem with "solr.XXX" class names and jars in SOLR_HOME/lib

Jars placed in SOLR_HOME/lib seem to be loaded twice, which causes problems trying to use solr.XXXXXX class names in schema.xml.

If the full class name is used, it works.

Steps to recreate on an extracted Solr 5.2.1 download. This was done on Windows, so I used backslashes as path separators:

bin\solr start
bin\solr create -c foo -d sample_techproducts_configs
bin\solr stop -all

Add the following to server\foo\conf\schema.xml, just before the </schema> end tag:

    <fieldType name="icu_test" class="solr.TextField">
      <analyzer> 
        <tokenizer class="solr.ICUTokenizerFactory"/>
      </analyzer>
    </fieldType>

Create a new directory – server\solr\lib.
Copy icu4j-54.1.jar and lucene-analyzers-icu-5.2.1.jar from contrib\analysis-extras to server\solr\lib.

bin\solr start

Note an exception in the logging tab:
java.lang.NoClassDefFoundError: org/apache/lucene/analysis/icu/segmentation/ICUTokenizer

At this point, if the class name is changed from solr.ICUTokenizerFactory to org.apache.lucene.analysis.icu.segmentation.ICUTokenizerFactory and solr is stopped and started, then everything is OK.