Description:
------------
hi
file_exists() return false on locked file with flock()!!
its ok on php 7.2 but after that its have problem...

just run this test file 2 time 
in second time its not detect file exist because its locked with flock()

Test script:
---------------
 <?php
error_reporting(0);
echo unlink("test.txt");
echo "<=unlink\r\n";
echo "\r\n>";
echo $exist = file_exists("test.txt");<<=== bug is here
echo "<=exist\r\n";
if ($exist)
{
   echo "!!!";
   echo "\r\n";
   sleep(1111);
   //exit();
}
echo "\r\n>";
echo $file = fopen("test.txt","w+");
echo "<=fopn\r\n";

// exclusive lock
echo "\r\n>";
echo $lockkk = flock($file,LOCK_EX);
echo "<=lock\r\n";
if ($lockkk) {
	 echo ">";
  echo fwrite($file,"Add some text to the file.");
  echo "<=fwrite\r\n";
  echo ">";
  echo fflush($file);
  echo "<=fflush\r\n";
  sleep(1000);
  // release lock
  flock($file,LOCK_UN);
} else {
  echo "Error locking file!";
}
echo "end:";
echo fclose($file);
sleep(100);
?> 

Expected result:
----------------
fisrt run (and lock text.txt) sleep...
result : 
><=unlink

><=exist

>Resource id #5<=fopn

>1<=lock
>26<=fwrite
>1<=fflush

second run (file already lock..)
>1<=unlink

><=exist

><=fopn

><=lock
Error locking file!end:

OK result in php 7.2 :
><=unlink

>1<=exist
!!!

Actual result:
--------------
-