readline crash with custom .inputrc

[Matthias Klose]

This was reported for Debian in https://bugs.debian.org/968703 for the
interactive Python interpreter, however I also see it with gdb, e.g. trying to
run ls in gdb. readline 8.1 is in use.

$ cat .inputrc
# Based on Brendan Miller's initial bash .inputrc
# INSTALL
# to install, rename this file to just ".inputrc"
# place this file in your home dir. e.g. ~/.inputrc
# restart your terminal. Then, bash's keybinding for editing
# should be like ErgoEmacs.
# If no key works, try replace all \e to \M-. That's means change Esc to Meta 
key.

set editing-mode emacs
"\M-j": backward-char
"\M-l": forward-char
"\M-u": backward-word
"\C-M-b": backward-word
"\M-o": forward-word
"\C-M-f": forward-word
"\M-g": kill-line
"\<S-delete>": kill-line
"\M-e": backward-kill-word
"\M-r": kill-word
"\M-f": delete-char
"\C-z": undo
"\<S-delete>": kill-region
"\M-c": copy-region-as-kill
"\<S-insertchar>": yank
"\C-v": yank
"\C-f": forward-search-history
"\M-:": reverse-search-history

just hitting return in interactive mode triggers the segfault.