See: http://forum.pmease.com/viewtopic.php?f=1&t=2843 for a full description of this issue.

Steps to reproduce:
1- Create a configuaration with a variable named "_test" with value "0"
2- Define a step with a node selection script that sets the value of a "_test" to "1".
2- In other areas of the step log the value of the variable.
3- In other steps log the value of the variable.

Expected result:
The log should show the value of "_test" as 1.

Actual result.
The log actually shows the value of "_test" as 0. i.e. the value set during the node selection script has not been correctly persisted.