download_chunks_concurrently function does not allow to setchecksum field indownload_kwargs. It also does not set it on its own so it takes the default value of"md5" (seeBlob._prep_and_do_download). Because ranged downloads do not return checksums it results in a lot of INFO messages (tens/hundreds):

INFO google.resumable_media._helpers - No MD5 checksum was returned from the service while downloading ...(which happens for composite objects), so client-side content integrity checking is not being performed.

To fix it set thechecksum field toNone which means no checksum checking for individual chunks. Note thattransfer_manager has its own checksum checking logic (enabled bycrc32c_checksum argument)

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Fixes#1358 🦕