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

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

third_party/git/contrib/git-shell-commands/help

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+if tty -s
+then
+	echo "Run 'help' for help, or 'exit' to leave.  Available commands:"
+else
+	echo "Run 'help' for help.  Available commands:"
+fi
+
+cd "$(dirname "$0")"
+
+for cmd in *
+do
+	case "$cmd" in
+	help) ;;
+	*) [ -f "$cmd" ] && [ -x "$cmd" ] && echo "$cmd" ;;
+	esac
+done