patch 8.0.0020
Problem:    The regexp engines are not reentrant.
Solution:   Add regexec_T and save/restore the state when needed.
diff --git a/src/version.c b/src/version.c
index 9e097af..b74ad2f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    20,
+/**/
     19,
 /**/
     18,