After 2.5 upgrade indexing stops with error "Changeset comment messages may not be null or empty"

Having an empty string in fields that do not support null will cause indexing to fail, with the following exception:
Error reported:

2011-02-15 14:58:05,359 ERROR [InitialPinger2 <Repository>] fisheye.app BaseRepositoryScanner-handleSlurpException - Problem processing revisions from repo <Repository> due to class org.hibernate.PropertyAccessException - Exception occurred inside setter of com.atlassian.fisheye.model.ChangesetComment.message
org.hibernate.PropertyAccessException: Exception occurred inside setter of com.atlassian.fisheye.model.ChangesetComment.message
.
.
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
.
.
Caused by: java.lang.IllegalArgumentException: Changeset comment messages may not be null or empty
at com.cenqua.crucible.model.ModelUtils.ensureNotNullOrEmpty(ModelUtils.java:8)
at com.atlassian.fisheye.model.ChangesetComment.setMessage(ChangesetComment.java:71)
... 36 more

The upgrade task is designed to take care of this, though in this case the check appears to have been missed.

Workaround:

1. Shutdown Fisheye
2. Backup your database
3. Run the sql below on your Fisheye database:

   update cru_changeset_comment set cru_message = ' ' where cru_message = ''