Description:
------------
FastCGI sent in stderr: "Parse error: syntax error, unexpected identifier "version" in php://input on line 1" when sending POST with the following POST-Data:
<?xml version="1.0" encoding="UTF-8"?>
<cXML>
</cXML>

If I am sending the following data to the script:
<?php echo 3 + 3; ?>
<test>test</test>

I am getting this result:
6
<test>test</test>

Somehow the XML get's interpreted without any logic within the script that is called.

Rebooting the docker container (8.0.3-fpm-alpine3.13) will solve the problem for a while - but after a couple hours the problem appears again.

Currently OpCache is enabled - also tryed to disable it.

Log does not show anything special:
10.240.0.100 - 29/Apr/2021:08:26:58 +0000 "POST /index.php" 200

Even if i place invalid code into the index.php:
<?php
thisShouldNotWork();

I am getting this result:
6
<test>test</test><br />
<b>Fatal error</b>:  Uncaught Error: Call to undefined function thisShouldNotWork() in /app/source/index.php:2
Stack trace:
#0 {main}
  thrown in <b>/app/source/index.php</b> on line <b>2</b><br />

But the log shows a successful POST - even a excaption was thrown:
10.240.0.100 - 29/Apr/2021:08:29:28 +0000 "POST /index.php" 200


There might be a related bug for 7.x: https://bugs.php.net/bug.php?id=80378

Test script:
---------------
The script (index.php) contains nothing but a die();:
<?php
die();

There is no logic at all within this script so I am asuming this error somewhere else.