Error when applying patch that removes submodule

Reproduction steps

on any existing repo that contains a submodule generate a diff that removes it:

$ git rm <submodule name>
$ git diff --staged > remove-submodule.patch

(I used git 2.25.1)
my generated patch looks like this:

diff --git a/.gitmodules b/.gitmodules
index 1b59123..e69de29 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +0,0 @@
-[submodule "submodule"]
-	path = submodule
-	url = ../submodule
diff --git a/submodule b/submodule
deleted file mode 160000
index xxxxx..0000000
--- a/fus-modules
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit xxxxxxxxxxxxxxxxxxxxxxxxxxx

And when running this small program that uses libgit2:
test.c.txt
built using
gcc test.c -lgit2 -L <path to libgit2>/libgit2/build/ -Wall -pedantic -I <path to libgit2>/libgit2/include/
And run like this:
LD_LIBRARY_PATH=<path to libgit2>/libgit2/build/ ./a.out <Path to repo> <path to patch file>

Expected behavior

It successfully applies the change

Actual behavior

Error applying patch: -1 no error

I checked also modifying the submodule and it fails too

Version of libgit2 (release number or SHA1)

1.3.0 and main ( d74d491481831ddcd23575d376e56d2197e95910 )

Operating system(s) tested

Linux (Ubuntu 20.04)

从附带的 test.c.txt 程序开始，使用删除或修改子模块的 patch 重现该故障。跟踪针对所报告的“-1 no error”结果的 patch 应用路径，然后验证提供的删除 patch 能在 Linux 上成功应用。该 issue 没有指出源文件或回归测试，因此定位相关实现和测试覆盖情况需要对 repository 进行研究。