I am running Mantis 1.1.1 and I tryed to upgrade to Mantis 1.2.0a3.
So I am not sure since which version this bug exists.

The main difference for the occurance are these 2 lines in the config_defualts_inc.php:

Mantis 1.1.1: $t_path = dirname( strip_tags( $_SERVER['PHP_SELF'] ) );
Mantis 1.2.0a3 :$t_file_path = str_replace( DIRECTORY_SEPARATOR, '/', FILE );

Both try to get the url of the file. This path is used later in all scripts for redirects. But there is a big difference in the result for my server architecutre.

the Mantis 1.1.1 lines gives the following result:
/mantis-staging/mantis
the Mantis 1.2 line give this result:
/opt/apache2/vhosts/<domain>/mantis/staging/mantisdev/config_defaults_inc.php

On the vhost are 2 alias defined:
<domain>/mantis => /opt/apache2/vhosts/<domain>/mantis/productive/
<domain>/mantis-staging => /opt/apache2/vhosts/<domain>/mantis/staging/

The problem is that the new Mantis version now create links like this:
https://<domain>/mantis/staging/mantisdev/my_view_page.php instead of
https://<domain>/mantis-staging/mantisdev/my_view_page.php

I am not sure how I can fix this. I tryed to set the variable $g_path in custom_inc.php. This way the first rederict from index.php works but all other links are still wrong.

Is there any otherway how I can fix this with custom variables?