Before this fix if a file was updated, but to the same length and
timestamp then the local backend would return the wrong (cached)
hashes for the object.
This happens regularly on a crypted local disk mount when the VFS
thinks files have been changed but actually their contents are
identical to that written previously. This is because when files are
uploaded their nonce changes so the contents of the file changes but
the timestamp and size remain the same because the file didn't
actually change.
This causes errors like this:
ERROR: file: Failed to copy: corrupted on transfer: md5 crypted
hash differ "X" vs "Y"
This turned out to be because the local backend wasn't clearing its
cache of hashes when the file was updated.
This fix clears the hash cache for Update and Remove.
It also puts a src and destination in the crypt message to make future
debugging easier.
Fixes#4031
b91c349cd5