Incorrect Schema Context for root path expressions

When a DFDL expression uses attempts to resolve a path relative to the document root, subsequent errors are reported as occurring at the document root, with no indication of where the faulty expression is.

Consider the following schema (attached):

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:dfdl="http://www.ogf.org/dfdl/dfdl-1.0/"
    xmlns:tns="urn:a"
    xmlns:ex="http://example.com"
    xmlns:fn="http://www.w3.org/2005/xpath-functions"
    targetNamespace="urn:a" >
<xs:include schemaLocation="org/apache/daffodil/xsd/DFDLGeneralFormat.dfdl.xsd" />

 <xs:annotation>
   <xs:appinfo source="http://www.ogf.org/dfdl/">
     <dfdl:format ref="tns:GeneralFormat"/>
   </xs:appinfo>
</xs:annotation>

<xs:element name="a1">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="b1" type="tns:b2"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:complexType name="b2">
  <xs:sequence>
    <xs:element name="b3" type="xs:int" dfdl:inputValueCalc="{ /c }" />
  </xs:sequence>
</xs:complexType>

</xs:schema>

Note that the IVC on element b3 makes reference to "/c", which does not exist. The error reported by Daffodil is:

[error] Schema Definition Error: No element corresponding to step {}c found. Possibilities for this step include: tns:a1.
Schema context: element reference tns:a1 Location line 1 in file:/home/bsloane/Documents/incubator-daffodil/test/test/a.dfdl.xsd

Which gives no indication that the problem is with b3. Further, where b3 to be in a different file than the schema root, the file displayed is still the file containing the schema root, not b3.