deflate on token returned 0 - rsync error: error in protocol data stream

[Heiko Schlittermann]

Hello,

we're using rsync on SLES 12 SP 5 on both sides (for detailed version
info see below) and we're experiencing the following issue on the
sender's side:

```
 etc/test/windows2019_x86_64_20210929.gz
 deflate on token returned 0 (22199 bytes left)
 rsync error: error in rsync protocol data stream (code 12) at token.c(427) [sender=3.1.3]
```

This happens with 1 out of about 4'000'000 files.
Transfer w/o compression works without any issues.

Question: Bug or feature?


The options we're using are:

    ```
    rsync',
    --rsh'        => "ssh -q -i $arg{privatekey} -l $arg{user}",
    --rsync-path' => "sudo $arg{user}",

    # content
    '--archive',    # implies --links (-l), --recursive (-r)
    '--hard-links',
    (map { ('--exclude' => $_) } @{ $arg{exclude} }),
    $arg{delete} eq 'yes' ? '--delete' : (),

    # transfer
    '--compress',
    '--partial',
    '--bwlimit' => $arg{bwlimit},

    # logging
    '--stats',
    '--verbose',
    '--log-file'        => $arg{rsynclogfile},
    '--log-file-format' => 'Modified %i %n%L',
    ```


Detailed version information:
```
rsync  version 3.1.3  protocol version 31
Copyright (C) 1996-2018 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 64-bit timestamps, 64-bit long ints,
    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, ACLs, xattrs, iconv, symtimes, prealloc, SLP

rsync comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
are welcome to redistribute it under certain conditions.  See the GNU
General Public Licence for details.
```

    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
--
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