FormDataCleanupModule leaves half the expired items

From the INFO loggings of multiple runs on a repository containing 134585 formdata nodes, it is seen that the form data cleanup only removes half the nodes.

Perhaps calling Node.remove() within a NodeIterator.nextNode() loop causes that (?).

Note that the FormDataCleanupModule is on 7.8 but the trunk's FormDataCleanupJob has the same logic.

Query: SELECT * FROM hst:formdata ORDER BY hst:creationtime ASC
Number of results found: 134585

[Run 1]
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 68504 items
Query: formdata//element(*,hst:formdata) order by @jcr:score ascending
Number of results found: 63987

[Run 2]
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 32000 items
Query: formdata//element(*,hst:formdata) order by @jcr:score ascending
Number of results found: 31986

[Run 3]
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 16000 items
Query: formdata//element(*,hst:formdata) order by @jcr:score ascending
Number of results found: 15984

[Run 4]
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 8000 items
Query: formdata//element(*,hst:formdata) order by @jcr:score ascending
Number of results found: 7983

[Runs 5, 6, 7, 8, 9]
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 4000 items
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 2000 items
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 1001 items
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():264] Done cleaning 980 items
INFO FormDataCleanupModule$FormDataCleanupJob.removeOldFormData():266] No timed out items