Buildout: namespaced development packages symlinked on Mac, but not on Debian 10

Hi everyone,

I have several namespaced packages configured with mr.developer in my buildout.cfg.

When I run buildout on my Mac, the namespace packages are correctly symlinked:

$ ls -lah src/senaite.core/src/senaite/core
total 16K
drwxr-xr-x 17 rbartl staff  544 Jul  4 19:52 .
drwxr-xr-x  4 rbartl staff  128 Jul  4 19:52 ..
-rw-r--r--  1 rbartl staff  224 Jul  4 19:52 __init__.py
drwxr-xr-x 20 rbartl staff  640 Jul  4 19:52 browser
drwxr-xr-x  3 rbartl staff   96 Jul  4 19:52 config
-rw-r--r--  1 rbartl staff 1,6K Jul  4 19:52 configure.zcml
drwxr-xr-x 10 rbartl staff  320 Jul  4 19:52 exportimport
drwxr-xr-x  3 rbartl staff   96 Jul  4 19:52 interfaces
lrwxr-xr-x  1 rbartl staff  108 Jul  4 19:52 listing -> /Users/rbartl/develop/ridingbytes/senaite/buildout.coredev/src/senaite.core.listing/src/senaite/core/listing
drwxr-xr-x 62 rbartl staff 2,0K Jul  4 19:52 locales
drwxr-xr-x  3 rbartl staff   96 Jul  4 19:52 profiles
-rw-r--r--  1 rbartl staff 5,6K Jul  4 19:52 setuphandlers.py
drwxr-xr-x  5 rbartl staff  160 Jul  4 19:52 skins
lrwxr-xr-x  1 rbartl staff  112 Jul  4 19:52 spotlight -> /Users/rbartl/develop/ridingbytes/senaite/buildout.coredev/src/senaite.core.spotlight/src/senaite/core/spotlight
lrwxr-xr-x  1 rbartl staff  114 Jul  4 19:52 supermodel -> /Users/rbartl/develop/ridingbytes/senaite/buildout.coredev/src/senaite.core.supermodel/src/senaite/core/supermodel
drwxr-xr-x 20 rbartl staff  640 Jul  4 19:52 tests
drwxr-xr-x 12 rbartl staff  384 Jul  4 19:52 upgrade

But when I run the same buildout on Debian 10, these symlinks are not created:

$ ls -lah src/senaite.core/src/senaite/core
total 72K
drwxr-xr-x 11 senaite senaite 4.0K Jul  4 21:01 .
drwxr-xr-x  3 senaite senaite 4.0K Jul  4 21:01 ..
drwxr-xr-x 18 senaite senaite 4.0K Jul  4 21:01 browser
drwxr-xr-x  2 senaite senaite 4.0K Jul  4 21:01 config
-rw-r--r--  1 senaite senaite 1.6K Jul  4 21:01 configure.zcml
drwxr-xr-x  5 senaite senaite 4.0K Jul  4 21:01 exportimport
-rw-r--r--  1 senaite senaite  224 Jul  4 21:01 __init__.py
-rw-r--r--  1 senaite senaite  547 Jul  4 21:01 __init__.pyc
drwxr-xr-x  2 senaite senaite 4.0K Jul  4 21:01 interfaces
drwxr-xr-x 56 senaite senaite 4.0K Jul  4 21:01 locales
drwxr-xr-x  3 senaite senaite 4.0K Jul  4 21:01 profiles
-rw-r--r--  1 senaite senaite 5.6K Jul  4 21:01 setuphandlers.py
-rw-r--r--  1 senaite senaite 6.4K Jul  4 21:01 setuphandlers.pyc
drwxr-xr-x  5 senaite senaite 4.0K Jul  4 21:01 skins
drwxr-xr-x  4 senaite senaite 4.0K Jul  4 21:01 tests
drwxr-xr-x  2 senaite senaite 4.0K Jul  4 21:01 upgrade

This is how my buildout.cfg looks like:

[buildout]
...
eggs =
    Plone
    senaite.core
    senaite.core.listing
    senaite.core.spotlight
    senaite.core.supermodel

extensions = mr.developer
develop =
sources = sources
auto-checkout = *

[sources]
senaite.core = git git://github.com/senaite/senaite.core.git pushurl=git@github.com:senaite/senaite.core.git branch=2.x
senaite.core.listing = git git://github.com/senaite/senaite.core.listing.git pushurl=git@github.com:senaite/senaite.core.listing.git branch=2.x
senaite.core.spotlight = git git://github.com/senaite/senaite.core.spotlight.git pushurl=git@github.com:senaite/senaite.core.spotlight.git branch=2.x
senaite.core.supermodel = git git://github.com/senaite/senaite.core.supermodel.git 
pushurl=git@github.com:senaite/senaite.core.supermodel.git branch=2.x

...

These are the versions I use:

setuptools==42.0.2
zc.buildout==2.13.3

Has anyone encountered a similar problem?

Thanks for any hints.

Ramon