rsync 2.5.5, "unexpected tag failures", Solaris 2.6 vs. 2.8, "--b locking-io" workaround

[Madole, Dave BGI SF]

Hi,

I have been having a problem that seems related to previously reported
problems
but persists.

I am syncing from a 2.6 Solaris box to a 2.8 solaris box.  All are running
rsync 2.5.5.

When I sync (commands simplified for example, always using rsh):

2.8box% rsync -e rsh 2.6box:/path/path/stuff/ /path/path/newstuff/

i.e., the 2.6 box is the server, I get spurious, persistent but inconsistent
"unexpected tag <some number>" failures.  This is, unfortunately, on the 2.8
box, the way I have to do it.

When I sync:

2.6box% rsync -e rsh /path/path/stuff/ 2.8box:/path/path/newstuff/

(the 2.8box is the server), it works.  But the 2.6 box isn't where the
script runs.

The first command ALSO works if I use the "--blocking-io" option, 

2.8box%rsync -e rsh 2.6box:/path/path/stuff/ /path/path/newstuff/
--blocking-io

but I'm not sure what the possible side-effects of that might be.  (I picked
up from the CVS archive that there was some kind of relationship between a
"socketpair" Solaris bug and the "--blocking-io" option, so tried it, but
that seemed many versions ago).

I am not doing the builds myself - sysadmins are doing it.  Is there
anything special they
need to do in the 2.6 build to avoid my having to use the "--blocking-io"
flag?

Thanks,

Dave Madole