Root Cause:
When the ivy.xml file specified in the Ivy Build Trigger is a 'delivered' ivy.xml file, extended revision matching does not work because the dependency revision id is not dynamic (see line 441 of IvyBuildTrigger.java).

We are using delivered ivy.xml files as these contain the published revision in the info element, whereas our ivy.xml files from source code do not (the publishing revision is calculated based on the `buildnumber` ant task for ant)

Workaround:
After publising, we run XSLT on the delivered ivy.xml file to copy the `revContraint` attribute over the top of the `rev` attribute in the `dependancy` elements. The XSLT is attached, so others can implement the workaround.

Suggested fix:
The `captures` method should use the revision constraint rather than the revision for the dependency, though I don't know how to retrieve this via the Ivy API.