Why are files synced again and again when not using -a?

[André Hänsel]

Hi,

usually I use rsync with -a but recently I used it without this option and
discovered that the same files are synced over and over again (as shown by
-v). Of course the rsync algorithm avoids the traffic but the files are all
listed.

As soon as I use -a for one time those files are not transferred again, even
when I remove the -a again.

So I suspect, when building the file list, rsync doesn't take into account
that it won't be able to transfer some attributes anyway (because of missing
-a) and tries again to transfer them.

Is this the desired behaviour?

This is valid for rsync  version 2.6.9  protocol version 29.

Regards,
André