updated for version 7.4.423
Problem:    expand("$shell") does not work as documented.
Solution:   Do not escape the $ when expanding environment variables.
diff --git a/src/version.c b/src/version.c
index 31d1b34..d8ed2a0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    423,
+/**/
     422,
 /**/
     421,