using AptPkg to map from binary package to source package

[Roderick Schertler <roderick@argon.org>]

Using AptPkg (but not AptPkg::Source, I don't want to assume the user
has downloaded source info), is there a better way to obtain the name of
the source package which provides a particular binary package than using
the info in $cache->{$binary_package}{VersionList}[0]{FileList}[0] to
read the available record and parse it from there?

-- 
Roderick Schertler
roderick@argon.org