patch 8.2.0808: not enough testing for the terminal window

Problem:    Not enough testing for the terminal window.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #6069)  Fix memory
            leak.
diff --git a/src/terminal.c b/src/terminal.c
index 3fcd659..0a5ccbc 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -3047,7 +3047,7 @@
 #endif
 	    else
 	    {
-		term->tl_title = vim_strsave(strval);
+		term->tl_title = strval;
 		strval = NULL;
 	    }
 	    VIM_CLEAR(term->tl_status_text);