Default Endian convention change between XE15 and XE16

After installing both XE15 and XE16 on one of our Linux clusters, we realized that the simple code here

real(kind=8)::a
a=123456789d0
open(10,file='bin.dat', form='unformatted')
write(10) a
close(10)
end

does not produce the same output (byte order) in the XE15 and XE16 environments.

Has a default value for the FORT_CONVERT.ext, FOR_CONVERTn and/or F_UFMTENDIAN environment variables changed from 15 or 16? Or does this point at an error in our installation?