merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/t/t7500/add-comments

@@ -0,0 +1,4 @@
+#!/bin/sh
+echo "# this is a new comment" >> "$1"
+echo "# and so is this" >> "$1"
+exit 0

third_party/git/t/t7500/add-content

@@ -0,0 +1,3 @@
+#!/bin/sh
+echo "commit message" >> "$1"
+exit 0

third_party/git/t/t7500/add-content-and-comment

@@ -0,0 +1,5 @@
+#!/bin/sh
+echo "commit message" >> "$1"
+echo "# comment" >> "$1"
+exit 0
+

third_party/git/t/t7500/add-signed-off

@@ -0,0 +1,3 @@
+#!/bin/sh
+echo "Signed-off-by: foo <bar@frotz>" >> "$1"
+exit 0

third_party/git/t/t7500/add-whitespaced-content

@@ -0,0 +1,8 @@
+#!/bin/sh
+sed -e 's/|$//' >>"$1" <<\EOF
+
+ |
+commit message  	 |
+
+EOF
+exit 0

third_party/git/t/t7500/edit-content

@@ -0,0 +1,4 @@
+#!/bin/sh
+sed -e "s/intermediate/edited/g" <"$1" >"$1-"
+mv "$1-" "$1"
+exit 0