Ticket: https://trac.macports.org/ticket/56254
Upstream-Status: Backport [This change is present in recent versions of MySQL 5.7 and later.]
--- mysql-5.6.39/sql-common/client_authentication.cc-	2018-04-08 18:42:13.000000000 -0400
+++ mysql-5.6.39/sql-common/client_authentication.cc	2018-04-08 19:19:37.000000000 -0400
@@ -84,7 +84,7 @@
 
   if (mysql->options.extension != NULL &&
       mysql->options.extension->server_public_key_path != NULL &&
-      mysql->options.extension->server_public_key_path != '\0')
+      mysql->options.extension->server_public_key_path[0] != '\0')
   {
     pub_key_file= fopen(mysql->options.extension->server_public_key_path,
                         "r");