Catch JournalReader.next() violations in Mode.COMMITS
JournalReader.next() is specified as an Iterator and should be throwing
NSEs. This is not the case when we ask for only commits, as the
corresponding check is done only in hasNext() and thus we would give out
uncommitted entries.
Fix this by adding an override to check for this condition.
JIRA: CONTROLLER-2106
Change-Id: I1f391cc19b9674646786c93656b83519e0f1f47b
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit
86ff19a91c2d4aa71f88135898ebc75fd3caee85)