During refactoring of the function mysqlnd_stream_write_w_header() it was

During refactoring of the function mysqlnd_stream_write_w_header() it was
found that there is a bug in the way the data is sent, although a very rare
one which will only affect very large queries which have length 16777214. The
communication will hang. A way to test it is to execute the following:
./php -r '$c=mysqli_connect("127.0.0.1","root","root","test");
$q="insert into test.tblob values(\"".str_repeat("a",256*256*256-1-34)."\")";
$c->query($q);'