Per official policy, updates from versions older than two TLS releases
are not supported.
Finding the implicit marker is a bit tricky. The user might try to
upgrade from a really old version that doesn't have tag_summary table
and mistakenly think it's new and allow upgrade. So turning the check
logic into a boolean AND where it must be new enough to have
change_tag_def table AND new enough not to have tag_summary table.
Change-Id: I5ff9630a6539a587a47930847e108ac53757106f
4bde067722