pkgversions doesn't handle multi-arch packages

I'm using the following buildout.cfg:

	[buildout]
	parts =
		pkgversions

	[pkgversions]
	recipe = c2c.recipe.pkgversions
	zlib1g-dev =

Running buildout results in the following error:

	$ bin/buildout
	While:
	  Installing.
	  Getting section pkgversions.
	  Initializing section pkgversions.
	Error: The package zlib1g-dev is not installed.

dpkg says I have zlib1g-dev installed (for amd64):

	$ dpkg -l |grep zlib1g-dev
	ii  zlib1g-dev:amd64                      1:1.2.7.dfsg-13                    amd64        compression library - development

so does apt-get:

	root@winserver:~# apt-get install zlib1g-dev
	Reading package lists... Done
	Building dependency tree
	Reading state information... Done
	zlib1g-dev is already the newest version.
	0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


I'm doing this on a debian 7 machine...