rewriter gets confused by element name "group"

[VladimirAlexiev]

this function

declare function local:rdf_groups ($url as xs:string, $study) {
  for $i in $study/clinical_results/baseline/group_list/group ###
  let $gr := fn:concat($url, "/group/", $i/@group_id/substring(.,2))
    # first char of @group_id is B=baseline, O=outcome, P=period, etc.
    # But the description is the same, so we identify them by the remaining numeric index
    construct {
      <{$url}> cto:group <{$gr}>.
      $gr a cto:Group;
        dc:title {$i/title/text()};
        dc:description {$i/description/text()}.      
    }
};

causes this error at the second line marked ###:

line 417:9 no viable alternative at input 'in'
line 417:56 no viable alternative at input 'group'
Parse error: java.lang.Exception: Errors for Parser. Translation aborted.
java.lang.Exception: Errors for Parser. Translation aborted.
        at net.sf.xsparql.rewriter.XSPARQLProcessor.process(XSPARQLProcessor.java:232)
        at net.sf.xsparql.Main.rewriteQuery(Main.java:197)
        at net.sf.xsparql.Main.main(Main.java:111)

Workaround: change it to this ugly longhand:

  for $i in $study/clinical_results/baseline/group_list/*[name()="group"]