nano: %n crash fix for 10.13

Fix crash from the usage of %n in
dynamic format strings on High Sierra

Formula/nano.rb

@@ -20,6 +20,15 @@ class Nano < Formula
   depends_on "gettext"
   depends_on "ncurses"
 
+  # Fix crash from usage of %n in dynamic format strings on High Sierra
+  # Patch credit to Jeremy Huddleston Sequoia <jeremyhu@apple.com>
+  if MacOS.version >= :high_sierra
+    patch :p0 do
+      url "https://raw.githubusercontent.com/macports/macports-ports/b76d1e48dac/editors/nano/files/secure_snprintf.patch"
+      sha256 "57f972940a10d448efbd3d5ba46e65979ae4eea93681a85e1d998060b356e0d2"
+    end
+  end
+
   def install
     system "./autogen.sh" if build.head?
     system "./configure", "--disable-debug",