As detailed in the previous commit, it's important to cache the
package manager used in the cache manifest. If we don't, we'll end
up reusing the wrong metadata cache which won't have any metadata in
it for the new package manager.
"release": self.release,
"mirror": self.mirror,
"architecture": self.architecture,
+ "package_manager": self.distribution.package_manager(self).executable(self),
"packages": sorted(self.packages),
"build_packages": sorted(self.build_packages),
"package_directories": [