RPM won't create a subpackage when there is no %files section

[jnovy]

Describe the bug
Any subpackage, even a meta-package which only ships dependencies and no files will fail to get generated quietly. The rpmbuild will end successfully but the declared subpackage is simply not created even though it's declared in spec file - if it is missing an empty %files section.

To Reproduce
Steps to reproduce the behavior:

1. define any meta package shipping only deps, no files
2. skip definition of %files in spec
3. build the spec - subpackage is missing.

Please link or attach the packages or spec files involved.

Expected behavior
A defined subpackage in spec should be generated despite missing %files section or rpmbuild should fail the build.