If a sign text has colour, editing the sign causes the sign text in the editing GUI to be the respective colour, but that is not the case if sign is glowing.
Steps to reproduce:
1. Apply glow ink on a sign.
2. Edit it.
Notice how in the edit GUI, the text is plain black instead of glowing.
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We're tracking this issue in MC-227965, so this ticket is being resolved and linked as a duplicate.
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