GNU tar 1.13.17 --overwrite works "wrong"

[Patterson, Ross]

The NEWS file for GNU tar 1.13.17 says:

        version 1.13.16 - Paul Eggert, 1999-12-13.

        * By default, tar now refuses to overwrite existing files when
          extracting files from an archive; instead, it removes them before
          extracting.  There is one exception: existing nonempty directories
          are not removed, nor are their ownerships or permissions extracted.
          This fixes some longstanding security problems.

          The new --overwrite option enables the old default behavior.

        ...

The second paragraph implies that "tar -x --overwrite" will behave exactly 
the same in 1.13.17 as "tar -x" in levels up to 1.13.15.  I've got a case 
where it doesn't, and it's a problem I can't seem to resolve.  Specifically, 
my company sells a product that includes a tar archive as the distribution 
vehicle.  The archive contains several independently-selectable components, 
organized in a directory tree much as you'd expect - directory "a" contains 
the "a" component files, "b" contains "b", etc.  When we install, we want to 
install all  the files for the components that the user chooses, and all in 
the same directory.  Just to complicate matters, there are some files that are 
present in more than one component (identical), and we want tar to silently 
replace one copy with another (because we KNOW that they're identical).  The 
following works on releases prior to 1.13.16:

        mkdir /install_target_dir
        ln -s /install_target_dir /install_target_dir/a
        ln -s /install_target_dir /install_target_dir/b
        ... more links, one for each component ...
        tar xzfp dist.tar.Z a b ... more components, as chosen by the user ...
        rm -f /install_target_dir/a
        rm -f /install_target_dir/b
        ... more cleanup ...

The effect we're looking for is to have all the files from the chosen 
components installed into /install_target_dir, and tar used to follow the 
symlinks and "make it so".  This was even deliberate behavior - "info tar" for 
1.12 says:

        Options to Prevent Overwriting Files
        ....................................
           Normally, `tar' writes extracted files into the file system without
        regard to the files already on the system; i.e., files with the same
        names as archive members are overwritten when the archive is extracted.
        If the name of a corresponding file is a symbolic link, the file
        pointed to by the symbolic link will be overwritten instead of the
        symbolic link itself (if this is possible). ...

GNU tar 1.13.17 does exactly what we don't want - it replaces the 
carefully-built symlinks with directories, and all the component files wind up 
in these new directories.  The 1.13.16 
--overwrite option appears to be intended to restore the old behavior,