Receiving newly generated block while downloading blockchain causes error

[miguelfreitas]

If during blockchain downloading a newly generated block is received it causes an error like that:

received block c84ded9d8c28a8471603e710d67264247083eb9965cff6912c01a14a1394750d
ERROR: CheckTransaction() : spam signed by unknown user
ERROR: CheckBlock() : CheckTransaction failed
ERROR: ProcessBlock() : CheckBlock FAILED
Misbehaving: 75.101.62.225:28333 (0 -> 100) DISCONNECTING
disconnecting node 75.101.62.225:28333

The node is not misbehaving. The block is valid. It is just that the user signing is not yet known.

Before validating the block against this spam transaction rule we must check height or current blockchain status to prevent this error.