When a users wants to install a package that itself is excluded or its
dependency is excluded, it fails the build. There is no known workaround
for this shorcoming of our current design.
Therefore, remove a package from the list of excluded if it is
explicitly mentioned in a blueprint. This will not solve the issue with
dependencies, but it will create a possibility of a workaround.
Also, introduce regression test to verify the bug fix and hook it into
CentOS CI (this issue was reported against RHEL, but CentOS runs on AWS
so it is better to verify the fix there).
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