Excerpted from idea shared by packger,

• Use the value specified by a --specfile option, if present.
• Use the component name discovered from git (as this really should be the spec file name for Fedora packages.
• Use the last component of CWD.

The possible use case for this issue is, sometimes, packagers could put upstream renamed SPEC file into packge repository during development. Hence, there could be more than one SPEC files including the package's.

The option --specfile could be a shared option which is available for all build related commands, for both local build or remote build in Koji.

# Search the files for the first one that ends with ".spec"
is a very bad choice , should try pick packaname.spec first .

I also got some headaches when I copy the original spec to .new.spec , ( I want preserve vim syntax so I choose .spec extension , as also mention in https://bugzilla.redhat.com/show_bug.cgi?id=1243546#c8

seems fixed according https://bugzilla.redhat.com/show_bug.cgi?id=1243546#c14
and
https://pagure.io/rpkg/pull-request/592