When following a journal-based log, it was possible for the worker
goroutine, which reads the journal using the journal context and sends
entry data down the message channel, to be scheduled after the function
which started it had returned. This could create problems, since the
invoking function was closing the journal context object and message
channel before it returned, which could trigger use-after-free segfaults
and write-to-closed-channel panics in the worker goroutine.
Make the cleanup in the invoking function conditional so that it's only
done when we're not following the logs, and if we are, that it's left to
the worker goroutine to close them.
Signed-off-by: Nalin Dahyabhai <nalin@redhat.com> (github: nalind)
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