If a user is running in a downgraded compatibility mode and calls conn->reconfigure() for any setting, for example, setting cache size, the system will return an error saying the system must be quiescent if there are any outstanding transactions. It should only return an error if the user is actually trying to change the compatibility setting.

The bug is that reconfigure is passed in the current running configuration string and the new setting added on at the end so the compatibility mode being anything other than the default hits the check in wt_conn_compat_config. That code needs to be restructured to only return an error if the value is changing.