Don't count 0-length RELAY_DATA cell as valid
Pointed out by Roger: The CIRC_BW OVERHEAD field currently counts a DATA cell on a valid stream but with 0 length as valid but 100% overhead. Since this can be injected arbitrarily by an end point, and should not happen in normal operation, it should not be counted as valid circuit data.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information