multi_ack_detailed is enabled. The server always sends NAK after 'done'
if there is no common base found.
+Instead of 'ACK' or 'NAK', the server may send an error message (for
+example, if it does not recognize an object in a 'want' line received
+from the client).
+
Then the server will start sending its packfile data.
----
- server-response = *ack_multi ack / nak
+ server-response = *ack_multi ack / nak / error-line
ack_multi = PKT-LINE("ACK" SP obj-id ack_status)
ack_status = "continue" / "common" / "ready"
ack = PKT-LINE("ACK" SP obj-id)
nak = PKT-LINE("NAK")
+ error-line = PKT-LINE("ERR" SP explanation-text)
----
A simple clone may look like this (with no 'have' lines):