This Plugin gives some very nice benefits, like running scripts in Transitions.
Sample - This actually get hold on a clone and changes the "Task Type" field to "Clone", whereas on the Master it is "Master"
import com.atlassian.jira.ComponentManager import com.atlassian.jira.issue.customfields.manager.OptionsManager def componentManager = ComponentManager.instance def optionsManager = componentManager.getComponentInstanceOfType(OptionsManager.class) def cf = customFieldManager.getCustomFieldObjects(issue).find {it.name == 'Task Type'} def fieldConfig = cf.getRelevantConfig(issue) def optionClone = optionsManager.getOptions(fieldConfig).find {it.value == "Clone"} issue.setCustomFieldValue(cf, optionClone)