Curious serial console behavior on armv7 running -current

While connecting a serial console session between two Raspberry Pi2
machines some strange output emerged.

The connection was via ssh to a Pi2 running stable/12 connected 
via cu through a usb serial adapter to a Pi2 running -current. 
When the connection became complete the screen filled with pages of

...
Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:Password:

Eventually I typed control-c and got

Jun 29 22:28:46 www login[945]: in prompt_tty(): caught signal 2
Jun 29 22:28:46 www login[945]: pam_authenticate(): Conversation failure
Login incorrect

Eventually the normal login prompt returned.

Not sure what to make of it, but it sure looked odd....
I think the flood of password prompts came from the -current machine.

Thanks for reading,

bob prohaska