ssh sessions close spontaneously on rpi2

[bob prohaska]

Can anybody reproduce the following behavior on RPI2 ?

Boot the machine multi-user and start two ssh login sessions.

On one, start a top session, as a placeholder. On the second,
su to root, cd to /usr/ports and run
make -j8 clean > clean.log &

Next, try to open another (this makes three) ssh connection. Log in,
and just watch. 

On my test box at FreeBSD 12.0-CURRENT (RPI2) #10 r325987 the connection
fails within a couple of minutes; the login session terminates without
explanation and the connection closes. 

No errors are on the serial console, /var/log/messages records nothing
related. Ssh sessions started prior to starting make clean seem unaffected.

Thanks for reading,

bob prohaska