Weird interaction with git add -p and Notepad++ (git hangs)

[klylesatepic]

• I was not able to find an open or closed issue matching what I'm seeing

Previously reported at microsoft/terminal#16553 and msys2/msys2.github.io#307.

Setup

• Which version of Git for Windows are you using? Is it 32-bit or 64-bit?
  Seen with both versions 2.42.0.windows.2 and 2.43.0.windows.1 (64-bit)

$ git --version --build-options
git version 2.43.0.windows.1
cpu: x86_64
built from commit: 4b968f3ea3b32a7bc50846bab49f3f381841d297
sizeof-long: 4
sizeof-size_t: 8
shell-path: /bin/sh
feature: fsmonitor--daemon

• Which version of Windows are you running? Vista, 7, 8, 10? Is it 32-bit or 64-bit?
  Seen on both version 10.0.19044.3930 and 10.0.22621.2861

$ cmd.exe /c ver

Microsoft Windows [Version 10.0.19044.3930]

• What options did you set as part of the installation? Or did you choose the
  defaults?

# One of the following:
> type "C:\Program Files\Git\etc\install-options.txt"
> type "C:\Program Files (x86)\Git\etc\install-options.txt"
> type "%USERPROFILE%\AppData\Local\Programs\Git\etc\install-options.txt"
> type "$env:USERPROFILE\AppData\Local\Programs\Git\etc\install-options.txt"
$ cat /etc/install-options.txt

Editor Option: VIM
Custom Editor Path:
Default Branch Option: main
Path Option: Cmd
SSH Option: OpenSSH
Tortoise Option: false
CURL Option: WinSSL
CRLF Option: CRLFAlways
Bash Terminal Option: MinTTY
Git Pull Behavior Option: Rebase
Use Credential Manager: Enabled
Performance Tweaks FSCache: Enabled
Enable Symlinks: Disabled
Enable Pseudo Console Support: Disabled
Enable FSMonitor: Enabled

• Any other interesting things about your environment that might be related
  to the issue you're seeing?

I don't think so, but I'm happy to answer further questions.

Details

• Which terminal/shell are you running Git from? e.g Bash/CMD/PowerShell/other

Git Bash in Windows Terminal

• What commands did you run to trigger this issue? If you can provide a
  Minimal, Complete, and Verifiable example
  this will help us understand the issue.

1. Open Git Bash in Windows Terminal
2. Navigate to a git repository
3. Make changes in at least two separate places in a file
4. Run GIT_EDITOR='"C:\Program Files\Notepad++\notepad++.exe" -multiInst -notabbar -nosession -noPlugin' git add -p to interactively stage parts of the file
   • Obviously you will need Notepad++ installed, and you may need to adjust the path to it
5. Type e to edit the first hunk (Notepad++ will open)
6. Make whatever change you like within one of the new lines (starting with a plus)
7. Save and close Notepad++
8. See that git moves on and prompts for the next hunk
9. Try to type n to skip the next hunk (or anything else)
10. See that git is stuck (Ctrl+C won't interrupt it)

The same issue happens with git add -i instead of git add -p, but requires more steps between steps 4/5.

The issue does not happen if any of the following are true:

• You use vanilla Git Bash instead of Git Bash in Windows Terminal

• You use cygwin instead of Git Bash in Windows Terminal (with a slightly different GIT_EDITOR value to account for differences in path handling)

• You only edit the last hunk

• You use a terminal editor instead of Notepad++ (I tried vim and nano)

• You use /c/Windows/System32/notepad.exe instead of Notepad++

  • The bug still happens if you just use 'notepad', which is a shell script in Git Bash located at /usr/bin/notepad

• What did you expect to occur after running these commands?

Input would be accepted for dealing with the next hunk, and git would not hang.

• What actually happened instead?

Input is not accepted (or at least not echoed), and git hangs.

• If the problem was occurring with a specific repository, can you provide the
  URL to that repository to help us with testing?

Not repository specific.