patch 8.0.0927: if a terminal job sends a blank title "running" is not shown

Problem:    If a terminal job sends a blank title "running" is not shown.
Solution:   When the title is blank make it empty.

src/terminal.c

@@ -1503,6 +1503,11 @@ handle_settermprop(
     {
 	case VTERM_PROP_TITLE:
 	    vim_free(term->tl_title);
+	    /* a blank title isn't useful, make it empty, so that "running" is
+	     * displayed */
+	    if (*skipwhite((char_u *)value->string) == NUL)
+		term->tl_title = NULL;
+	    else
 		term->tl_title = vim_strsave((char_u *)value->string);
 	    vim_free(term->tl_status_text);
 	    term->tl_status_text = NULL;

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    927,
 /**/
     926,
 /**/