Reported in firebird-devel by Jean-Marc Bottura:

- I do a backup with gbak BASE.FDB -> BASE.FBK : ok

- Then a restore/backup BASE.FBK -> BASE1.FDB -> BASE1.FBK :
there are a lot of differences in the format between BASE.FBK and
BASE1.FBK ( a lot of 0x0500 added at the beginning of the FBK, the order
of the fields in the tables records is inverted, and so on ...)

- But if I do another restore/backup BASE1.FBK -> BASE2.FDB ->
BASE2.FBK : surprise ! the BASE2.FBK is exactly the same as the original
BASE.FBK (except date and time in the header)

- And if I do another restore/backup BASE2.FBK -> BASE3.FDB ->
BASE3.FBK : the BASE3.FBK is exactly the same as the BASE1.FBK

- And so on ...