Current session flag is incorrect

Problem/Motivation

The list of sessions on the session inspector page (via route session_inspector.manage) attempts to load the current session of the user.

This is because the SessionDeserializer defaults to using a SessionDeserializer::deserializePhP() method, which re-generates the session sid. It does prevent the user from losing their session as the session data is re-populated at the end of the method, but this is clearly flushing the data in the database.

This means that the current session sid is no longer present as it has been re-generated.

For the time being, the PHP ini setting can be changed from "php" to "php_binary" to change how this function works.

Steps to reproduce

Install the module.
Go to the session list page for the user.
Even with one session in place there is no "current" flag.

Proposed resolution

Look at the SessionDeserializer::deserializePhP() method and find a different way of deserialising the data for the "php" deserialization method.

Or, at least, ensure that the current session is not re-generated with a new session ID when running the SessionDeserializer::deserializePhP() method.

This method also needs to work with _other_ sessions in the session table, so we need to be careful not to copy one session onto another.

Remaining tasks

Write a test for this situation.