Linux build of "package_archive" fails

I’m building Blender from the blender-v2.91-release branch, SHA ec6a9322e87. Building headless works OK using “build headless”. But when I try to build the package archive with “build headless package_archive” I get many permission errors and it doesn’t build the tar. (Ubuntu 20.04 in WSL1.)

% make headless package_archive
...snipped...
make -C "/c/dss/Product/Horizon/ext-sources/blender/blender-official/build_linux_headless" -s package_archive
[100%] Generating release/Blender-2.91-ec6a9322e872-linux-x86_64.tar.xz
Failed to copy install directory: [('bin/2.91/datafiles/colormanagement/filmic', 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91/datafiles/colormanagement/filmic', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91/datafiles/colormanagement/filmic'")
...many more...
('bin/2.91/scripts/templates_py', 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91/scripts/templates_py', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91/scripts/templates_py'"), ('bin/2.91/scripts', 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91/scripts', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91/scripts'"), ('bin/2.91', 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64/2.91'"), ('bin/lib', 'Blender-2.91-ec6a9322e872-linux-x86_64/lib', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64/lib'"), ('bin/license', 'Blender-2.91-ec6a9322e872-linux-x86_64/license', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64/license'"), ('bin', 'Blender-2.91-ec6a9322e872-linux-x86_64', "[Errno 13] Permission denied: 'Blender-2.91-ec6a9322e872-linux-x86_64'")]
CMakeFiles/package_archive.dir/build.make:60: recipe for target 'release/Blender-2.91-ec6a9322e872-linux-x86_64.tar.xz' failed
make[4]: *** [release/Blender-2.91-ec6a9322e872-linux-x86_64.tar.xz] Error 1
make[4]: Target 'CMakeFiles/package_archive.dir/build' not remade because of errors.
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/package_archive.dir/all' failed

Removing the ../build_linux_headless/Blender-2.91-* dir doesn’t help.
Diffing bin/2.91 vs Blender-2.91-ec6a9322e872-linux-x86_64/2.91 shows no diffs, i.e. all is well.
If I comment out the exit 1 line in build_archive.py:45 then the archive is created and works fine.

I don’t think this is a new problem; it’s been happening for a while. Maybe the “permission denied” errors are from setting dest file metadata, since the generated archive actually works OK? I assume if it doesn’t happen for others it’s something specific about my system or my config; any help would be appreciated!