Currently we print "sha256 checksum failed for [file]. Expected X but
got Y".
This PR extends that message with file size and contents info:
"... but got Y. File size = 123456 bytes. Contents = b'abc...def'"
That way we can immediately see if the file was downloaded only
partially, or if we downloaded a text page instead of a binary, etc.
Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>
5f8c09fd33