SOLR-5442: Python client cannot parse proxied response when served by Tomcat.
SOLR-5445: Proxied responses should propagate all headers rather than the first one for each key.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1542335 13f79535-47bb-0310-9956-ffa450edef68