socket.c:2171: unexpected error

Description of problem:

Getting stuff like this in logs since the upgrade to 9.11.4-P2 from 9.11.2:

24-Sep-2018 00:32:13.012 general: error: socket.c:2171: unexpected error:
24-Sep-2018 00:32:13.013 general: error: internal_send: <client_ip>#49478: Invalid argument

I cannot reproduce the bug by a client request, but others can, as reported from another user: https://bugzilla.redhat.com/show_bug.cgi?id=1571059

I git bisected the problem to first bad commit: [5e375f8b] Use completely static-sized buffers

Trial and error lead to this patch which solved the problem for me: socket.c.diff

No more unexpected error log entries

Im running SunOS 5.11.3 on x86-64