patch 8.1.0973: pattern with syntax error gives threee error messages

Problem:    Pattern with syntax error gives threee error messages. (Kuang-che
            Wu)
Solution:   Remove outdated internal error.  Don't fall back to other engine
            after an error.

src/version.c

@@ -779,6 +779,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    973,
 /**/
     972,
 /**/