fixup! Bugfix: completed transformed-data read requests and VARCHUNK data buffers of returned de-transformed data are now properly freed cleaned up at the correct time during chunked reads. Previously, completed read reqests were freed immediately upon completion, invalidating the last varchunk returned to the user. Also, previous varchunk data buffers lent to the user were only freed upon a new varchunk arriving, leaving the last varchunk unfreed even if the first bug were fixed. Now, cleanup is done immediatly after any check_reads, including the final call that returns 0.