patch 8.0.0813: cannot use a terminal window while the job is running

Problem:    Cannot use Vim commands in a terminal window while the job is
            running.
Solution:   Implement Terminal Normal mode.
diff --git a/src/screen.c b/src/screen.c
index a1e8b5f..baedea7 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -3245,7 +3245,7 @@
 #endif
 
 #ifdef FEAT_TERMINAL
-    if (term_is_finished(wp->w_buffer))
+    if (term_show_buffer(wp->w_buffer))
     {
 	extra_check = TRUE;
 	get_term_attr = TRUE;