Currently, when checking whether the booted kernel is signed by the original vendor, convert2rhel just figures out that the booted kernel corresponds to a package named "kernel", it gets all "kernel" packages installed and looks at the signature of the first returned "kernel". That's obviously doesn't work on a system that has multiple kernels installed, each from a different vendor.

This bug was found by rhn-support-mlitwora.

Steps to reproduce:

• Get CentOS Linux 7
• Add OL 7 base repo
• Install a RHEL compatible kernel from the OL repo
• Boot into the newly installed kernel
• Run convert2rhel and observe that the conversion doesn't stop at the kernel compatibility check even though it should (because the kernel signature does not match the original system vendor - CentOS)

Acceptance criteria:

• The `_bad_kernel_package_signature` function is improved so that it does get a full NEVRA of the kernel package that corresponds to the booted kernel.
  • If there's more than one kernel installed (some of them may be even from a different vendor), the check picks up the one specific kernel that's currently loaded in order to verify its signature