$ cd /tmp
$ mkdir am-nocontext
$ cd am-nocontext
$ git init
Initialized empty Git repository in /tmp/am-nocontext/.git/
$ git config user.name "Joe Average"
$ git config user.email "joe@example.com"
$ printf "One\nTwo\nThree\n" > text.txt
$ cat text.txt
One
Two
Three
$ git add text.txt
$ git commit -m "Initial commit"
[master (root-commit) e2e0c16] Initial commit
 1 file changed, 3 insertions(+)
 create mode 100644 text.txt
$ git log --pretty=oneline
e2e0c16f6d31bc8e673494ecc92d1e8f377275aa (HEAD -> master) Initial commit
$ printf "2d\nwq\n" | ed text.txt
14
10
$ cat text.txt
One
Three
$ git diff
diff --git a/text.txt b/text.txt
index 4fcefbf..3146b8f 100644
--- a/text.txt
+++ b/text.txt
@@ -1,3 +1,2 @@
 One
-Two
 Three
$ git commit -am "Removing second line"
[master 27e6e8b] Removing second line
 1 file changed, 1 deletion(-)
$ git log --pretty=oneline
27e6e8bdc3ecbecc17f5ec1407f97f1977054461 (HEAD -> master) Removing second line
e2e0c16f6d31bc8e673494ecc92d1e8f377275aa Initial commit
$ git format-patch -U0 HEAD^
0001-Removing-second-line.patch
$ cat 0001-Removing-second-line.patch
From 27e6e8bdc3ecbecc17f5ec1407f97f1977054461 Mon Sep 17 00:00:00 2001
From: Joe Average <joe@example.com>
Date: Tue, 5 May 2020 18:17:52 +0700
Subject: [PATCH] Removing second line

---
 text.txt | 1 -
 1 file changed, 1 deletion(-)

diff --git a/text.txt b/text.txt
index 4fcefbf..3146b8f 100644
--- a/text.txt
+++ b/text.txt
@@ -2 +1,0 @@ One
-Two
-- 
2.26.2

$ git reset --hard HEAD^
HEAD is now at e2e0c16 Initial commit
$ git log --pretty=oneline
e2e0c16f6d31bc8e673494ecc92d1e8f377275aa (HEAD -> master) Initial commit
$ git am 0001-Removing-second-line.patch
Applying: Removing second line
error: patch failed: text.txt:2
error: text.txt: patch does not apply
Patch failed at 0001 Removing second line
hint: Use 'git am --show-current-patch=diff' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
$ git am --abort
$ git diff
$ git log --pretty=oneline
e2e0c16f6d31bc8e673494ecc92d1e8f377275aa (HEAD -> master) Initial commit
$ git apply --verbose 0001-Removing-second-line.patch
Checking patch text.txt...
error: while searching for:
Two

error: patch failed: text.txt:2
error: text.txt: patch does not apply
$ git log --pretty=oneline
e2e0c16f6d31bc8e673494ecc92d1e8f377275aa (HEAD -> master) Initial commit
$ git diff
$ patch -p 1 -i 0001-Removing-second-line.patch
patching file text.txt
$ git diff
diff --git a/text.txt b/text.txt
index 4fcefbf..3146b8f 100644
--- a/text.txt
+++ b/text.txt
@@ -1,3 +1,2 @@
 One
-Two
 Three
$ exit