Off-by-one error in http archive patch parsing logic with patch created by `git diff -U0`

Description of the bug:

Bazel's patch logic is not able to handle patches created with git diff -U0. It appears new content are inserted one line before it's intended location.

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Consider the following workspace setup (patch-bug.zip).

> ls
BUILD      WORKSPACE  bad.patch  good.patch

> cat BUILD

> cat WORKSPACE
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "good_bazel_skylib",
    patch_args = ["-p1"],
    patches = ["//:good.patch"],
    sha256 = "66ffd9315665bfaafc96b52278f57c7e2dd09f5ede279ea6d39b2be471e7e3aa",
    urls = [
        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.4.2/bazel-skylib-1.4.2.tar.gz",
        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.4.2/bazel-skylib-1.4.2.tar.gz",
    ],
)

http_archive(
    name = "bad_bazel_skylib",
    patch_args = ["-p1"],
    patches = ["//:bad.patch"],
    sha256 = "66ffd9315665bfaafc96b52278f57c7e2dd09f5ede279ea6d39b2be471e7e3aa",
    urls = [
        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.4.2/bazel-skylib-1.4.2.tar.gz",
        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.4.2/bazel-skylib-1.4.2.tar.gz",
    ],
)

> cat bad.patch
diff --git a/BUILD b/BUILD
index 3a0651a..4d2b717 100644
--- a/BUILD
+++ b/BUILD
@@ -16,0 +17 @@ filegroup(
+    tags = ["foo"],

> cat good.patch
diff --git a/BUILD b/BUILD
index 3a0651a..4d2b717 100644
--- a/BUILD
+++ b/BUILD
@@ -16,2 +16,3 @@ exports_files([
 filegroup(
+    tags = ["foo"],
     name = "test_deps",

Good patch is created with git diff -U1 and bad patch is created with git diff -U0. (Note, it does appear to me that line number 16 in bad patch is weird. I am not entirely sure what the semantic should be for this case. Could this be a bug with git instead?)

Then we have

> bazel query @bad_bazel_skylib//:all
ERROR: /private/var/tmp/_bazel_tgeng/58da6ac068090c85809c6d5045e5abcc/external/bad_bazel_skylib/BUILD:16:4: indentation error
ERROR: /private/var/tmp/_bazel_tgeng/58da6ac068090c85809c6d5045e5abcc/external/bad_bazel_skylib/BUILD:16:20: syntax error at 'outdent': expected expression
ERROR: package contains errors: : indentation error
ERROR: Evaluation of query "@bad_bazel_skylib//:all" failed
Loading: 0 packages loaded

> bazel query @good_bazel_skylib//:all
@good_bazel_skylib//:bzl_library
@good_bazel_skylib//:distribution
@good_bazel_skylib//:lib
@good_bazel_skylib//:test_deps
@good_bazel_skylib//:version
@good_bazel_skylib//:workspace
Loading: 0 packages loaded

Specifically, with the bad patch, the content of BUILD file becomes the following, where the inserted line is at a wrong location.

exports_files([
    "LICENSE",
    "MODULE.bazel",
    "WORKSPACE",
])

    tags = ["foo"],
filegroup(
    name = "test_deps",
    testonly = True,
    srcs = [
        "BUILD",
        "//lib:test_deps",
        "//rules:test_deps",
        "//toolchains/unittest:test_deps",
    ] + glob(["*.bzl"]),
)

Which operating system are you running Bazel on?

macOS

What is the output of bazel info release?

release 6.2.1

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse master; git rev-parse HEAD ?

No response

Is this a regression? If yes, please try to identify the Bazel commit where the bug was introduced.

No response

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response