For the record, it was Jason who started this fix.

Sat, Mar 05, 2005 at 02:46:38AM +0000, Allen Briggs:
> 
> Module Name:	src
> Committed By:	briggs
> Date:		Sat Mar  5 02:46:38 UTC 2005
> 
> Modified Files:
> 	src/sys/netinet: ip_output.c
> 
> Log Message:
> Fix checksum offload for fragmented packets.  From John Heasley
> on gnats-bugs in PR kern/29544.
> Tested with an NFS client using default rwsize on an NFS server
> with wm(4) interface configured IP4CSUM,TCP4CSUM,UDP4CSUM.
> Prior revision required the server to have checksum offload disabled.
> 
> 
> To generate a diff of this commit:
> cvs rdiff -r1.144 -r1.145 src/sys/netinet/ip_output.c
> 
> Please note that diffs are not public domain; they are subject to the
> copyright notices on the relevant files.