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.
diff --git a/src/terminal.c b/src/terminal.c
index 9115ac3..0024d5f 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -1503,7 +1503,12 @@
     {
 	case VTERM_PROP_TITLE:
 	    vim_free(term->tl_title);
-	    term->tl_title = vim_strsave((char_u *)value->string);
+	    /* 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;
 	    if (term == curbuf->b_term)
diff --git a/src/version.c b/src/version.c
index 00aedce..d8a93da 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    927,
+/**/
     926,
 /**/
     925,