patch 7.4.1510

Problem:    Channel test fails on AppVeyor.
Solution:   Wait longer than 10 msec if needed.

src/testdir/test_channel.vim

@@ -395,11 +395,21 @@ func s:raw_one_time_callback(port)
 
   " The message are sent raw, we do our own JSON strings here.
   call ch_sendraw(handle, "[1, \"hello!\"]", {'callback': 's:HandleRaw1'})
+  for i in range(50)
     sleep 10m
+    if s:reply1 != ''
+      break
+    endif
+  endfor
   call assert_equal("[1, \"got it\"]", s:reply1)
   call ch_sendraw(handle, "[2, \"echo something\"]", {'callback': 's:HandleRaw2'})
   call ch_sendraw(handle, "[3, \"wait a bit\"]", {'callback': 's:HandleRaw3'})
+  for i in range(50)
     sleep 10m
+    if s:reply2 != ''
+      break
+    endif
+  endfor
   call assert_equal("[2, \"something\"]", s:reply2)
   " wait for up to 500 msec for the 200 msec delayed reply
   for i in range(50)

src/version.c

@@ -743,6 +743,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1510,
 /**/
     1509,
 /**/