The config returned by koji mock-config does not specify correct package manager even if the tag has it set in the extra data.

$ koji call getBuildConfig f29-build
{'arches': 'armv7hl i686 x86_64 aarch64 ppc64le s390x',
 'extra': {'mock.package_manager': 'dnf'},
 'id': 3428,
 'locked': False,
 'maven_include_all': False,
 'maven_support': False,
 'name': 'f29-build',
 'perm': None,
 'perm_id': None}
$ koji mock-config --tag f29-build --arch x86_64 | grep package_manager
$

For the CLI command this is definitely a bug, as there's no other way for caller to specify it.

It would be nice if koji.genMockConfig honored the setting as well or there was some other API that would simplify it. Right now to get proper config a user needs to call getBuildConfig and then genMockConfig (example). This leaks a lot of details.