NullPointerException selecting NONE for Cascading Select Field

Steps to reproduce

1. Create a custom field Cascading Select
2. Add the options into it
3. Create an issue
4. Select 'NONE' for the Cascading Select custom field
   The issue successfully created without exception
5. Edit the same issue and select 'NONE' for the Cascading Select custom field again
   The following error appear and the update fail:

   2012-05-04 18:18:58,904 http-8503-6 ERROR kahloun.foong 1098x176x1 2zrt38 127.0.0.1 /secure/QuickEditIssue.jspa [jira.bc.issue.DefaultIssueService] Exception occurred editing issue: java.lang.NullPointerException
   java.lang.NullPointerException
   	at com.atlassian.jira.issue.customfields.impl.CascadingSelectCFType.getChangelogValue(CascadingSelectCFType.java:390)
   	at com.atlassian.jira.issue.customfields.impl.CascadingSelectCFType.getChangelogValue(CascadingSelectCFType.java:69)
   	at com.atlassian.jira.issue.fields.CustomFieldImpl.getChangelogValue(CustomFieldImpl.java:378)
   	at com.atlassian.jira.issue.fields.CustomFieldImpl.updateValue(CustomFieldImpl.java:418)
   	at com.atlassian.jira.issue.fields.CustomFieldImpl.updateValue(CustomFieldImpl.java:399)
   	at com.atlassian.jira.issue.managers.DefaultIssueManager.updateFieldValues(DefaultIssueManager.java:589)
   	at com.atlassian.jira.issue.managers.DefaultIssueManager.updateIssue(DefaultIssueManager.java:554)
   	at com.atlassian.jira.bc.issue.DefaultIssueService.update(DefaultIssueService.java:272)
   	at com.atlassian.jira.bc.issue.DefaultIssueService.update(DefaultIssueService.java:246)
   	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   

Workaround

1. Shutdown JIRA
2. Backup and modify the file <jira-install>\atlassian-jira\WEB-INF\classes\templates\plugins\fields\edit\edit-cascadingselect.vm from

   <select class="select cascadingselect-parent" id="${customField.id}" name="${customField.id}">
           <option class="default-option" value="">$i18n.getText("common.words.pleaseselect")</option>
           <option class="default-option" value="-1">$i18n.getText("common.words.none")</option>
           #foreach ($option in $configs.options.rootOptions)
               #if(!$option.disabled || $option.disabled == false || ($selectedParent && $selectedParent == $option.optionId.toString()))
                   <option class="option-group-$option.optionId" value="$option.optionId"#if ($selectedParent && $selectedParent == $option.optionId.toString()) selected="selected"#end>$cfValueEncoder.encodeForHtml($option.value)</option>
               #end
           #end
       </select>
       <select class="select cascadingselect-child" id="${customField.id}:1" name="${customField.id}:1">
           <option class="default-option" value="">$i18n.getText("common.words.pleaseselect")</option>
           <option class="default-option" value="-1">$i18n.getText("common.words.none")</option>
           #foreach ($parentOption in $configs.options.rootOptions)
               <option class="option-group-$parentOption.optionId" value="">$i18n.getText("common.words.pleaseselect")</option>
               <option class="option-group-$parentOption.optionId" value="-1">$i18n.getText("common.words.none")</option>
   

   to

   <select class="select cascadingselect-parent" id="${customField.id}" name="${customField.id}">
           <option class="default-option" value="">$i18n.getText("common.words.none")</option>
           <!-- <option class="default-option" value="-1">$i18n.getText("common.words.none")</option> -->
           #foreach ($option in $configs.options.rootOptions)
               #if(!$option.disabled || $option.disabled == false || ($selectedParent && $selectedParent == $option.optionId.toString()))
                   <option class="option-group-$option.optionId" value="$option.optionId"#if ($selectedParent && $selectedParent == $option.optionId.toString()) selected="selected"#end>$cfValueEncoder.encodeForHtml($option.value)</option>
               #end
           #end
       </select>
       <select class="select cascadingselect-child" id="${customField.id}:1" name="${customField.id}:1">
           <option class="default-option" value="">$i18n.getText("common.words.none")</option>
           <!-- <option class="default-option" value="-1">$i18n.getText("common.words.none")</option> -->
           #foreach ($parentOption in $configs.options.rootOptions)
               <option class="option-group-$parentOption.optionId" value="">$i18n.getText("common.words.none")</option>
               <!-- <option class="option-group-$parentOption.optionId" value="-1">$i18n.getText("common.words.none")</option> -->
   

3. Restart JIRA
   This modification will remove the 'Please select' in the option and replace it with the word 'None'