Thanks to Fabian Joswig <fabian.joswig@wwu.de>

When calling BDIO_seek the very last record of a bdio file cannot be
accessed due to ipt < length(fb.records)) and ipt starting at 1. If I
understand it correctly you would have to change the condition to ipt
<= length(fb.records)) in order to be able to access the last
record. I noticed this because I did not attach an additional record
containing the hash and then BDIO_seek immediately returns false.