With prefetch-on-open enabled, the task doing the prefetching was using
non-positional (i.e. streaming) reads. If the main (non-prefetch) thread
was also using non-positional reads, these two would conflict, because
inputstreams are not thread-safe for non-positional reads.
In the case of an encrypted filesystem, this could cause JVM crashes,
etc, as underlying cipher buffers were freed underneath the racing
threads. In the case of a non-encrypted filesystem, less severe errors
would be thrown. The included unit test reproduces the latter case.
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