[Bug report] Hash mismatch error for file

Encountering error, "ERROR Hash mismatch for file /acl-anthology/bin/../build/anthology-files/pdf/emoji/2022.emoji-1.0.pdf, downloaded from https://aclanthology.org/2022.emoji-1.0.pdf. was f30c68cc should be 36bb53fe" for several pdf files while generating the anthology via make mirror command.

Start by reproducing the failure with `make mirror`, using the listed PDF URL and hash-mismatch message as the first checkpoint. Trace the mirror-generation path that validates downloaded files and determine why several PDFs differ from their expected hashes; done means the affected files no longer produce hash-mismatch errors during generation.

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