Thanks very much for the detailed bug report!
This bug was introduced by r784 (see #68): we set a maximum packet size for client packets, and your clipboard packet is bigger than that... (something I never tested)
The fix in r994 is to increase the maximum client packet size to 1MB and to force zlib compression on those clipboard packets.
I am unsure whether it makes sense to allow anything bigger than 1MB as clipboard contents over the network... I guess that if we do not, what we should do is drop the clipboard contents rather than the connection!
(so keeping this ticket open for now)