child_process_stream: split incoming chunks to reproduce bug

nvim/child_process_stream.lua

@@ -40,7 +40,19 @@ function ChildProcessStream:read_start(cb)
     if err then
       error(err)
     end
-    cb(chunk)
+
+    -- Send the chunks through <X> chars at a time. The read_start callback
+    -- should be happy to receive the data in chunks of any size as long as
+    -- they are in the correct order.
+    -- NOTE: sometimes this causes the functional tests to freeze up in weird
+    -- places, but also sometimes it causes a reproduction of the error seen on
+    -- OSX
+    local chunk_size = 8192
+    local i = 1
+    while i < #chunk do
+      cb(chunk:sub(i, i + chunk_size - 1))
+      i = i + chunk_size
+    end
   end)
 end