Git 2.51.0(2) ignoring custom diff tool settings

[ordnko]

Existing issues matching what you're seeing

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

Git for Windows version

git version 2.51.0.windows.2
cpu: x86_64
built from commit: ade1f1c136682d1bed178d573dc4dc40dca11623
sizeof-long: 4
sizeof-size_t: 8
shell-path: D:/git-sdk-64-build-installers/usr/bin/sh
feature: fsmonitor--daemon
libcurl: 8.16.0
OpenSSL: OpenSSL 3.5.3 16 Sep 2025
zlib: 1.3.1
SHA-1: SHA1_DC
SHA-256: SHA256_BLK
default-ref-format: files
default-hash: sha1

Windows version

Windows 11

Windows CPU architecture

x86_64 (64-bit)

Additional Windows version information

Microsoft Windows [Version 10.0.26200.6584]

Options set during installation

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

Other interesting things

After reverting to Git 2.49.0, the expected behavior was restored, and the configured diff tools were respected.

Terminal/shell

CMD

Commands that trigger the issue

>"C:\Program Files\Git\bin\git.exe" difftool --gui --find-renames --find-copies --no-prompt "764c5b9fd3a7012f23522f697510eef471f01bad" "6dde90ec6ea14ecf343e4b5da78ef1f31b3e8e5f" -- "agent_redirection.go"

This message is displayed because 'diff.tool' is not configured.
See 'git difftool --tool-help' or 'git help config' for more details.
'git difftool' will now attempt to use one of the following tools:
kompare emerge vimdiff nvimdiff
2 files to edit
===
>"C:\Program Files\Git\bin\git.exe" config get diff.tool
bc4
===
>"C:\Program Files\Git\bin\git.exe" config get --global diff.guitool
bc4

Expected behaviour

I would expect the diff to be opened using Beyond Compare 4.

Actual behaviour

The diff has opened in gvim.

Repository

No response