Cards configuration disappear while migrating from greenhopper 4.2.1 to greenhopper 4.3

This issue was raised from: https://support.atlassian.com/browse/GHS-583

Steps to replicate the problem:
1. Configure some new custom fields and add them to card, summaries and list views in greenhopper (version 4.2.1).
2. See if there are on those views.
3. Then stop JIRA, upgrade greenhopper to version 4.3 and restart JIRA.
4. Then go to greenhopper views and check if those custom fields are present on card, summaries and list views.
5. The configuration for the cards in version 4.2 has been set to default after upgrade to 4.3.