Migration from a 2.7.2 to 4.3-RC1 fails on MySQL

This is not related to DW at all. I get the errors when migrators kick in, before the DW appears.

Steps to reproduce:

• download and unzip a clean Apache Tomcat version 7.0.32
• download the 2.7.2 war and unzip
• add the JDBC drivers and modify the hibernate file to point to a MySQL clean database
• put the content of the prepared war into /webapps/xwiki directory
• start tomcat
• import the default 2.7.2 XAR
• stop tomcat (If you are using Tomcat 6 you will get a huge stacktrace. see 272stop.txt attached). I might be hitting http://xwiki.markmail.org/thread/uhoo3if3tsauwmuj - see Sergiu's comment)
• download the latest 4.3-RC1 war (also tested with SNAPSHOT) and unzip in a new directory
• add the JDBC drivers to the unpacked war and modify the hibernate file to point to the MySQL database created above
• delete the webapps/xwiki dir content and place the content of the new 4.3 war in webapps/xwiki.
• start tomcat and access it to trigger migrators. You will get an error (see starting43.txt)

Tested the same method on PostgreSQL and Oracle and the migrator didn't fail.

I got the stacktrace (closing272.txt) when closing 2.7.2 on Tomcat 6 with ALL databases and no stacktrace when using Tomcat 7