When building in koji or copr and a test fails, the verbose output from
the tests can be very useful in determining the cause. Print the output
from failing tests, borrowing heavily from the upstream code¹ used when
running tests in Travis CI².
This could be done inline in %check rather than in a separate script.
The downside is that rpm would include each command invocation of the
loop in the output, which adds a lot of useless text to the already
copious build output.
¹ https://git.kernel.org/pub/scm/git/git.git/plain/ci/print-test-failures.sh
² https://travis-ci.org/git/git
