This should fix the current frequent issue on the debian loader [1]
- loader retrieve badly the length information from the content-length header
- We check for download size with that incorrect data
- so download call function fails because it checks the local size and it's difference
all of this for the sha1_git computation which needs the length.
But we do not really need that hash (nor blake).
So simplifying by removing will actually fix [1]
[1] https://sentry.softwareheritage.org/share/issue/49d464bee7b24ad080598b32cd3eb9a8/
[2] https://sentry.softwareheritage.org/organizations/swh/issues/?project=9&query=is%3Aunresolved&sort=freq&statsPeriod=14d