Bug#375849: apt: continue prompt occasionally fails to continue

[Justin Pryzby <justinpryzby@users.sourceforge.net>]

Package: apt
Version: 0.6.44.2
Severity: normal

Since some recent apt update, the "Do you want to continue [Y/n]"
prompt when packages are removed or new ones installed for a
dist-upgrade fails to continue:

$ sudo strace -p 10004
Process 10004 attached - interrupt to quit
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1
read(0, "\r", 1024)                     = 1

I expect that a single keystroke would cause it to continue.

It seems that my terminal is in a strange mode; not only does it send
\r instead of \n, it doesn't wait for a newline.

read(0, "a", 1024)                      = 1
read(0, "s", 1024)                      = 1
read(0, "d", 1024)                      = 1
read(0, "f", 1024)                      = 1
read(0, "\r", 1024)                     = 1
read(0, "d", 1024)                      = 1
read(0, "d", 1024)                      = 1

I don't think I did anything special or strange to cause this...