ModeShape 3.8.0 not releasing JDBC connections to the pool

In Overlord, we upgraded S-RAMP to use ModeShape 3.8.0. Immediately after, it appears ModeShape/Infinispan is not returning connections to the connection pool (at least for Tomcat and Jetty). Here's an example setup w/ a Tomcat DataSource, Infinispan config, and ModeShape config:

https://gist.github.com/brmeyer/83b4b33647fdb5e61303

If I temporarily reduce the connection pool to something like 5, S-RAMP will hang when attempting to persist the 5th artifact. A few things to note, and things I've tried:

• If we keep all configs and the ISPN version the same, but revert to MS 3.6.0, this issue does not occur.
• Not using JTA – ISPN is setup to use its DummyTransactionManagerLookup.
• ISPN defaults to autoCommit="true", so I set defaultAutoCommit="true" on the Tomcat DS as well.
• Using ISPN 5.2.10

The hanging occurs on a Session#save. The JcrXaSession shows the following nodes, prior to the save: https://gist.github.com/brmeyer/e089ff05f02cb5357999

Note that the saves work fine up until the nth persist, where n is the # of max connections in the jdbc pool.