Another bug introduced by the recent re factoring in this area.
Untested hack patch.
Looks like I was just getting confused by the fact that our test solr.xml starts with numShards in it - which is just some cruft mistake.
Commit 1533806 from Mark Miller in branch 'dev/trunk'
[ https://svn.apache.org/r1533806 ]
SOLR-5328: Errant numShards in test solr.xml
Commit 1533807 from Mark Miller in branch 'dev/branches/branch_4x'
[ https://svn.apache.org/r1533807 ]