michael@stroeder.com wrote:

FWIW: With back-mdb I ran 64 iterations without this error. Testing with back-bdb and back-hdb the failure occurs on my system after max. 10 iterations.

This sounds like it may be related to the issue I've been chasing down with ITS#7052. It appears that this bug was caused by the patch for ITS#6024. I'm about to revert that patch in master. Please re-test with d4b3c2af ...