transcription and diplomatic divs with empty elements as contents don't display content about iip-production

[emylonas]

@birkin masa0940c.xml has no transcription. It does have a diplomatic component.

            <div type="edition" subtype="diplomatic" ana="b1">
                <p>h<gap reason="lost" unit="character" extent="unknown"/></p>
            </div>
            <div type="edition" subtype="transcription" ana="b1">
                <p> </p>
            </div>

We shouldn't have any at that have no text at all.

[birkin]

fixed in commit a09bac4#diff-9d7bb3eed8f06d586707c11aa8a40e06R98-R112