Fix bug infinite loop when pasting multilines fo code in Ruby 2.6

[osyo-manga]

Description

Fix bug infinite loop when pasting multilines fo code in Ruby 2.6.
This is not reproduced in Ruby 2.7.
Changes added in https://github.com/ruby/irb/pull/242/files#diff-612b926e42ed78aed1a889ac1944f7d22229b3a489cc08f837a7f75eca3d3399R155 are also reflected in Ruby 2.6.

This bug was found by @ima1zumi, Thanks!! :)

Steps to reproduce

1. Run irb
2. Pasting multilines of code

def hoge
end

3. Infinite loop

Result of irb_info

$ RBENV_VERSION=2.6.8 bundle exec irb
irb(main):001:0> irb_info
=>
Ruby version: 2.6.8
IRB version: irb 1.3.8.pre.11 (2021-10-09)
InputMethod: ReidlineInputMethod with Reline 0.2.8.pre.11
RUBY_PLATFORM: x86_64-linux
LANG env: ja_JP.UTF-8

irb(main):002:0>

Terminal Emulator

• GNOME Terminal 3.36.2

Setting Files

None setting files.

[aycabta]

OK, great!