If the post subset cmap12 table is equivalent to another cmap subtable don't include the 12 table in the final subset. Matches change https://github.com/fonttools/fonttools/pull/2146 from fontTools.
NotoColorEmoji.ttf uses two cmap subtables
Format 14 | Platform ID 0 | Platform Encoding ID 5
Format 12 | Platform ID 3 | Platform Encoding ID 10
This combination results in the cmap table being dropped during subsetting despite being valid/required.
Garret Rieger
Qunxin Liu
ckitagawa-work