Cannot add a ZWiki to a Zope 2.13.22 instance

[tseaver]

After installing Zope 2.13.22 into a virtualenv:

$ /opt/Python-2.7.9/bin/virtualenv /tmp/zwiki
New python executable in /tmp/zwiki/bin/python
Installing setuptools, pip...done.
$ /tmp/zwiki/bin/easy_install -i http://download.zope.org/Zope2/index/2.13.22/ Zope2
Searching for Zope2
Reading http://download.zope.org/Zope2/index/2.13.22/Zope2/
Best match: Zope2 2.13.22
Downloading https://pypi.python.org/packages/source/Z/Zope2/Zope2-2.13.22.zip
Processing Zope2-2.13.22.zip
Writing /tmp/easy_install-TDMWMj/Zope2-2.13.22/setup.cfg
Running Zope2-2.13.22/setup.py -q bdist_egg --dist-dir /tmp/easy_install-TDMWMj/Zope2-2.13.22/egg-dist-tmp-RMdvZU
warning: no previously-included files matching '*.dll' found anywhere in distribution
warning: no previously-included files matching '*.pyc' found anywhere in distribution
warning: no previously-included files matching '*.pyo' found anywhere in distribution
warning: no previously-included files matching '*.so' found anywhere in distribution
creating /tmp/zwiki/lib/python2.7/site-packages/Zope2-2.13.22-py2.7.egg
Extracting Zope2-2.13.22-py2.7.egg to /tmp/zwiki/lib/python2.7/site-packages
Adding Zope2 2.13.22 to easy-install.pth file
Installing runzope script to /tmp/zwiki/bin
Installing zopectl script to /tmp/zwiki/bin
Installing zpasswd script to /tmp/zwiki/bin
Installing addzope2user script to /tmp/zwiki/bin
Installing mkzopeinstance script to /tmp/zwiki/bin
...
Finished processing dependencies for Zope2

I can install ZWiki into an 'INSTANCE_HOME/Products' directory:

$ /tmp/zwiki/bin/mkzopeinstance -d /tmp/zwiki-instance
Please choose a username and password for the initial user.
These will be the credentials you use to initially manage
your new Zope instance.

Username: zope
Password: 
Verify password:
$ cd /tmp/zwiki-instance/Products/
$ git clone https://github.com/simonmichael/ZWiki.git
Cloning into 'ZWiki'...
remote: Counting objects: 10939, done.
remote: Total 10939 (delta 0), reused 0 (delta 0), pack-reused 10939
Receiving objects: 100% (10939/10939), 22.94 MiB | 1.60 MiB/s, done.
Resolving deltas: 100% (6526/6526), done.
$ cd ..
$ bin/zopectl fg
2015-03-17 22:12:15 INFO ZServer HTTP server started at Tue Mar 17 22:12:15 2015
    Hostname: 0.0.0.0
    Port: 8080
2015-03-17 22:12:16 INFO Zope Ready to handle requests

But when I try to add a ZWiki in the ZMI (via http://localhost:8080/manage_addProduct/ZWiki/addwikiform):

2015-03-17 22:12:32 ERROR Zope.SiteErrorLog 1426644752.520.65415236047 http://localhost:8080/manage_addProduct/ZWiki/addwikiform
Traceback (innermost last):
  Module ZPublisher.Publish, line 138, in publish
  Module ZPublisher.mapply, line 77, in mapply
  Module ZPublisher.Publish, line 48, in call_object
  Module Shared.DC.Scripts.Bindings, line 322, in __call__
  Module Shared.DC.Scripts.Bindings, line 359, in _bindAndExec
  Module App.special_dtml, line 185, in _exec
  Module DocumentTemplate.DT_In, line 627, in renderwob
  Module Products.ZWiki, line 430, in listWikis
  Module Products.ZWiki, line 439, in listZodbWikis
AttributeError: ZWiki