Permission denied errors with --append-verify run as non-root user

[Knight, Dave]

I noticed that my latest  "syncHome" script log scontained a number of
unexpected "Permission denied" errors for some modified files.  The cause
seems to be that those files were read-only at the target.

The syncHome script is used to maintain a partial mirror of my home
directory tree on another host.

Further investigation and some experiments led me to suspect the
--append-verify functionality.  Specifically, those files were not rsync'd
when the --append-verify rsync flag was specified but were properly rsync'd
when --append-verify was NOT specified.

Other rsync scripts that use --append-verify and are run as root seem not
to exhibit this behavior.

FYI, I downloaded and built the "latest" version (rsync  version 3.2.3
 protocol version 31) and with this version of rsync, the modified files
are silently NOT rsync'd for both root and non-root users when
--append-verify is specified.  When --append-verify is not specified, the
updated files are rsync'd correctly.

That seems to me to be a serious bug, IMHO, because I "LIKE' to use
--append-verify to ensure that large files are copied entirely without
having to resync the entire file if there is an error.  If the
--append-verify option *silently fails* to rsync some updated files that
*should* be rsync'd, I cannot use --append-verify!

Please advise whether I am misunderstanding the purpose of, or misusing
the  --append-verify flag or if this is a bug.   It is really easy to
reproduce, BTW...

Dave Knight
Radford, VA
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