patch 9.1.0604: popup_filter during Press Enter prompt seems to hang

Problem:  popup_filter during Press Enter prompt seems to hang
Solution: Return early, when need_wait_return is set
          (Ernie Rael)

fixes: #15300
closes: #15301

Signed-off-by: Ernie Rael <errael@raelity.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/popupwin.c

@@ -2651,6 +2651,8 @@ f_popup_filter_yesno(typval_T *argvars, typval_T *rettv)
 	return;
 
     c = *key;
+    if (c == CAR && need_wait_return)
+	return;
     if (c == K_SPECIAL && key[1] != NUL)
 	c = TO_SPECIAL(key[1], key[2]);
 

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    604,
 /**/
     603,
 /**/