[viewvc-users] ViewVC tar missing a byte or two?

I'm trying to debug a problem we have with pulling source code to build RPMs
out of our CVS repo.  It may not be ViewCV related but I'm starting here as
I can't point to anything else yet.

Cvs and dev system are RHEL4, same patch.

We use something like

"wget -O demo-downloaded.tar.gz
http://cvs/viewvc/demo.tar.gz?view=tar&pathrev=$BRANCH "  to grab the source
with the correct TAG or branch.

 Then we 
"rpmbuild -tb demo-downloaded.tar.gz" to process the tarball with the
specfile inside and presto...we get an RPM.

But it fails on the tar ball as is.  If I unpack, then repack the tarball it
works.  

tar -xzvf demo-downloaded.tar.gz
tar -czvf demo-repack.tar.gz demo

What I find is the tarballs are slightly different in size.

tar -tzvf demo-downloaded.tar.gz
tar: Record size = 10 blocks
drwxr-xr-x viewvc/viewvc     0 2006-03-29 11:07:08 demo/
-rwxr-xr-x viewvc/viewvc   322 2006-03-29 11:07:08 demo/demo.spec
-rwxr-xr-x viewvc/viewvc   182 2005-07-11 16:51:51 demo/makefile
drwxr-xr-x viewvc/viewvc     0 2005-12-30 12:50:32 demo/src/
-rwxr-xr-x viewvc/viewvc   284 2005-12-30 12:50:32 demo/src/demo.c


-rw-r--r--   1 zelston psi_dev  609 Mar 29 11:42 demo-downloaded.tar.gz
-rw-r--r--   1 zelston psi_dev  647 Mar 29 12:13 demo-repack.tar.gz
-rwxr-x---   1 zelston psi_dev  622 Mar 29 12:19 demo-web.tar.gz
  


I've downloaded the repo from browsers, from curl and wget and I get the
same result from rpmbuild (failure).   After unpacking and repacking
rpmbuild works.

Is VIEWVC doing anything funky when packaging the tar?  Any ideas?

Thanks
-zac