rlwrap prompt disappears w/ readline 8.1

[Felix C. Stegerman]

Hi!

With libreadline8=8.0:

  $ rlwrap -C test python3 -c 'while True: print("you said", input(">>> "))'
  >>> foo
  you said foo
  >>> bar
  you said bar
  >>> ^D

With libreadline8=8.1:

  $ rlwrap -C test python3 -c 'while True: print("you said", input(">>> "))'
  foo
  you said foo
  bar
  you said bar
  >>> 

The ">>> " prompt is initially shown each time, but then disappears
from the output afterwards.  If I input "baz" next, I get:

  foo
  you said foo
  bar
  you said bar
  baz
  you said baz
  >>>

My analysis:

* readline 8.1 enables bracketed-paste by default;

* when bracketed-paste is enabled, rl_deprep_terminal() prints
  BRACK_PASTE_FINI ("\033[?2004l\r") to rl_outstream;

* this moves the cursor to the beginning of the line (instead of the
  position after the prompt), which causes the rlwrap prompt to be
  overwritten during rl_redisplay().

* thus, adding "set enable-bracketed-paste off" to my ~/.inputrc fixes
  the problem;

* THB I'm not entirely sure whether this is a bug in readline or in
  rlwrap, so I'm reporting it to both.

- Felix