When a chest is not open, its "hole" texture is on the top, meaning the top part has been flipped. When you watch the chest from under it, it has a "hole" texture under it. Possibly not a texture pack bug since texture pack worked fine before this snapshot.
Thank you for your report!
We're actually already tracking this issue in MC-161338, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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