Description:
------------
The example demonstrates a discrepancy in A+ mode between a file stream, and a php://temp stream.

According to docs, the file stream is correct, and php://temp is wrong here. 

Interesting this is not new, apparently all PHP versions do this, even HHVM:

https://3v4l.org/6KlYg

But both streams should behave the same, so something is off.

Test script:
---------------
<?php
function test($a) {
    fwrite($a, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ');
    fseek($a, 0);
    fwrite($a, '1234567890');
    fseek($a, 0);
    var_dump(fread($a, 1024));
    fclose($a);
}

$a = fopen('php://temp', 'a+');
test($a);

echo '-------------------' . PHP_EOL;

$a = fopen(tempnam(sys_get_temp_dir(), "hello"), 'a+');
test($a);

Expected result:
----------------
string(36) "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
-------------------
string(36) "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"

Actual result:
--------------
string(26) "1234567890KLMNOPQRSTUVWXYZ"
-------------------
string(36) "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"