Scrambled console on RPi3

[bob prohaska]

A few minutes ago I unplugged and replugged a PL2303 serial adapter in an
RPi3 running r329495. The serial console announced the disconnection with
ugen0.4: <vendor 0x067b product 0x2303> at usbus0 (disconnected)
uplcom0: at uhub1, port 2, addr 4 (disconnected)
uplcom0: detached

followed by  a torrent of unprintable garbage. Then it calmly announced

<vendor 0x067b product 0x2303> at usbus0
uplcom0 on uhub1
uplcom0: <vendor 0x067b product 0x2303, class 0/0, rev 1.10/4.00, addr 4> on usbus0

The displaying host is a Pi3 running the latest Raspbian. It's not clear
how much, if any, of the oddity is an artifact of the display. Experience
to date suggests none.
 
Far as I can tell the pl2303 and the host RPi3 are working normally. I've 
never done this experiment before on a Pi3, but have done it many times on
a Pi2 and nothing of the sort has happened.

Hope this is of interest to someone...

bob prohaska