Odd value on redirect_status (44)

Question

1. What does $_SERVER['REDIRECT_STATUS'] with value '44' mean?
2. Why would $_SERVER['REDIRECT_URL'] have a "/500.shtml" value?
3. I make no external redirect with mod_rewrite but $_SERVER have two different values for REQUEST_METHOD (POST and then GET); like if I made a POST request that then was redirected as a GET request. What is happening here?

I used the method described at http://blog.iosart.com/2004/05/26/fooling-apache/ to set some environment variables based on %{HTTP_HOST} value, and then multiplex between multiple PHP apps.

When hunting a bug with multipart/form-data POST requests, I found that PHP was getting these values from the Superglobals:

$_SERVER=array
(
    'CONTENT_LENGTH' => '1660'
    'CONTENT_TYPE' => 'multipart/form-data; boundary=----------------------------7e789ef7ac774b7689c602d8f67446dd'
    'CONTEXT_DOCUMENT_ROOT' => '/home/myphpapp/public_html'
    'CONTEXT_PREFIX' => ''
    'DOCUMENT_ROOT' => '/home/myphpapp/public_html'
    'GATEWAY_INTERFACE' => 'CGI/1.1'
    'HTTP_ACCEPT' => '*/*'
    'HTTP_ACCEPT_ENCODING' => 'gzip, deflate'
    'HTTP_CONNECTION' => 'keep-alive'
    'HTTP_HOST' => 'api.myphpapp.com'
    'HTTP_USER_AGENT' => 'Dalvik/1.6.0 (Linux; U; Android 4.4.2; Android SDK built for x86 Build/KK)'
    'HTTP_X_TOKEN' => 'prod'
    'MY_HTTP_HOST' => 'api.myphpapp.com'
    'PATH' => '/bin:/usr/bin'
    'QUERY_STRING' => ''
    'REDIRECT_MY_HTTP_HOST' => 'api.myphpapp.com'
    'REDIRECT_REDIRECT_REQUEST_METHOD' => 'POST'
    'REDIRECT_REDIRECT_STATUS' => '44'
    'REDIRECT_REDIRECT_UNIQUE_ID' => 'UxZd4zIcVQUAAFwqGD8AAAAG'
    'REDIRECT_STATUS' => '44'
    'REDIRECT_UNIQUE_ID' => 'UxZd4zIcVQUAAFwqGD8AAAAG'
    'REDIRECT_URL' => '/500.shtml'
    'REDIRECT_APP_SET' => 'api'
    'REDIRECT_APP_MODE' => 'production'
    'REMOTE_ADDR' => '100.101.102.103'
    'REMOTE_PORT' => '65446'
    'REQUEST_METHOD' => 'GET'
    'REQUEST_SCHEME' => 'http'
    'REQUEST_URI' => '/v1/2/controller/action'
    'SCRIPT_FILENAME' => '/home/myphpapp/public_html/index.php'
    'SCRIPT_NAME' => '/index.php'
    'SERVER_ADDR' => '50.51.52.53'
    'SERVER_ADMIN' => '[email protected]'
    'SERVER_NAME' => 'api.myphpapp.com'
    'SERVER_PORT' => '80'
    'SERVER_PROTOCOL' => 'HTTP/1.1'
    'SERVER_SIGNATURE' => ''
    'SERVER_SOFTWARE' => 'Apache'
    'UNIQUE_ID' => 'UxZd4zIcVQUAAFwqGD8AAAAG'
    'APP_SET' => 'api'
    'APP_MODE' => 'production'
    'PHP_SELF' => '/index.php'
    'REQUEST_TIME_FLOAT' => 1393974756.09
    'REQUEST_TIME' => 1393974756
    'argv' => array()
    'argc' => 0
)

My (simplified) .htaccess is:

FileETag None
Options -Indexes
Options +FollowSymLinks

RewriteEngine On

#Vary Host cheat http://blog.iosart.com/2004/05/26/fooling-apache/
RewriteRule .*  - [E=MY_HTTP_HOST:%{HTTP_HOST}]

RewriteCond %{ENV:MY_HTTP_HOST} ^myphpapp\.com$ [NC]
RewriteRule ^(.*)$ http://www.myphpapp.com/$1 [R=301,L]

RewriteRule ^ - [E=APP_MODE:production]

RewriteRule ^ - [E=APP_SET:none]
RewriteCond %{ENV:MY_HTTP_HOST} ^www\.myphpapp\.com$ [NC]
RewriteRule ^ - [E=APP_SET:home] []
RewriteCond %{ENV:MY_HTTP_HOST} ^api\.myphpapp\.com$ [NC]
RewriteRule ^ - [E=APP_SET:api]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php

I'm running Apache 2.4.7 & PHP 5.4.25 & index.php is a Yii 1.1.14 App

Answer 1

There was a bug in the http library i was using.

The boundary ending in multipart POST had an extra CRLF, and the Content-Length was 2 bytes greater than it should be... that's why Apache 2.4.7 sent 500 response and ALL the elements of php global $_SERVER had garbage inside..

Apache 2.4.3 seem to ignore the extra CRLF and wrong Content-Length in this particular case.