Stashing unstaged changes stashes everything

[AnrDaemon]

Type: Bug

-1. Create a repo.
0. Commit a few files (a and b).

1. Modify 2 files (a and b).
2. Stage the file a.
3. Add an untracked file c.
4. Stash the unstaged changes.

Expected behavior: the b is stashed.

Actual behavior: everything is stashed. That is, even the staged file a and untracked c.

Extension version: 17.3.1
VS Code version: Code 1.102.1 (7adae6a56e34cb64d08899664b814cf620465925, 2025-07-15T16:41:17.147Z)
OS version: Windows_NT x64 10.0.19045
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i3-8145U CPU @ 2.10GHz (4 x 2304)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	7.86GB (0.50GB free)
Process Argv	--folder-uri file:///d%3A/Profiles/anrdaemon/Documents/hk/invapi-php
Screen Reader	no
VM	0%

[AnrDaemon]

Possibly related #4490 (too bad it didn't pop up in related search).

The git version 2.45.2.windows.1 set to be used in VS Code Git ext.
Also git version 2.45.1 (Cygwin), which I use in console.

[Qbyte248]

This bug does not exist in version 17.1.1, i.e., it was introduced in 17.2.0, and still persists until version 17.3.2 and the current prerelease version 2025.7.2305.

[aliokan]

Still exisitng on 2025.9.1105. #4584