Export Plone content based on a catalog search (quintagroup.transmogrifier)

Question

In my Plone 4 site, I have installed quintagroup.transmogrifier (I tried both release 0.5 and the bleeding-edge github version) and collective.transmogrifier 1.5.

I found an example for an export based on a portal_catalog search here.

I have the following export configuration, registered as catalogsearch:

[transmogrifier]
pipeline =
    catalog
    fileexporter
    marshaller
    datacorrector
    portletsexporter
    writer
    EXPORTING

[catalog]
blueprint = quintagroup.transmogrifier.catalogsource
path = query= /Plone/some/existing/folder/

[fileexporter]
blueprint = quintagroup.transmogrifier.fileexporter

[marshaller]
blueprint = quintagroup.transmogrifier.marshaller

[datacorrector]
blueprint = quintagroup.transmogrifier.datacorrector
sources =
    marshall

[portletsexporter]
blueprint = quintagroup.transmogrifier.portletsexporter

[writer]
blueprint = quintagroup.transmogrifier.writer
prefix = structure

[EXPORTING]
blueprint = quintagroup.transmogrifier.logger
keys =
    _type
    _path

The idea is to specify the search expression when calling the transmogrifier:

$ bin/instance debug
>>> portal = app.Plone
>>> from collective.transmogrifier.transmogrifier import Transmogrifier
>>> tm = Transmogrifier(portal)
>>> tm('catalogsearch')
>>> tm('catalogsearch', catalog={'path': '/Plone/some/existing/folder/'})

However, both calls to the Transmogrifier object never return; I need to terminate them with Ctrl+C. Shouldn't this work, regardless of the debug session? What is wrong?