Ncml_handler fails when ascii data (or a server function result) is requested for renamed variables.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<netcdf xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" location="/ugrids/test4.nc">
    <variable name="rangeData" orgName="nodedata" shape="node" type="float"/>
</netcdf>

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<bes:request xmlns:bes="http://xml.opendap.org/ns/bes/1.0#" reqID="[http-8080-1:24:fvcom_1step.nc]">
  <bes:setContext name="xdap_accept">2.0</bes:setContext>
  <bes:setContext name="dap_explicit_containers">no</bes:setContext>
  <bes:setContext name="errors">xml</bes:setContext>
  <bes:setContext name="max_response_size">0</bes:setContext>
  <bes:setContainer name="catalogContainer" space="catalog">/ugrids/test4-rename-nodedata.ncml</bes:setContainer>
  <bes:define name="d1" space="default">
    <bes:container name="catalogContainer">
      <bes:constraint>rangeData</bes:constraint>
    </bes:container>
  </bes:define>
  <bes:get type="dods" definition="d1"  returnAs="ascii" />
</bes:request>

Dataset: test4-rename-nodedata.ncml
rangeData, <?xml version="1.0" encoding="ISO-8859-1"?>
<response reqID="[http-8080-1:24:foofoofoo]" xmlns="http://xml.opendap.org/ns/bes/1.0#">
    <getAscii>
        <BESError>
            <Type>2</Type>
            <Message>libdap exception building response: error_code = 1002: Failed to get values as ascii: An internal error was encountered in Float64.cc at line 163:
The incoming pointer does not contain any data.
Please report this to support@opendap.org
</Message>
            <Administrator>admin.email.address@your.domain.name</Administrator>
        </BESError>
    </getAscii>
</response>
BES server 18270: Status not OK, dispatcher returned value 2