[SOLVED] Plone does not checkout a development addon over SVN, buildout fails when applying develop.cfg

I intend to develop an add-on for Plone. From what I have gathered after reading the manuals, the best way to do so that is compatible with my development tools is by setting up a standalone SVN HTTP server and having Plone checkout my add-on's source code into its own directories.

Having read that, I started out by installing Mr. Bob and Plone's bobtemplates (pip install mr.bob bobtemplates.plone). Then I created on my SVN server a new directory, checked it out into a new directory in my local filesystem with svn checkout https://192.168.1.10/svn/SVN/plone-test/trunk, and initialized a new project this way:

~/plone/test/trunk$ mrbob -O plone.app.RAKK-test bobtemplates.plone:addon

Welcome to mr.bob interactive mode. Before we generate directory structure, some questions need to be answered.

Answer with a question mark to display help.
Values in square brackets at the end of the questions show the default value if there is no answer.


--> Author's name [FakeGitUserOrEmail]: RAKK

--> Author's email [FakeGitUserOrEmail]: rakk@example.com

--> Author's GitHub username:

--> Package description [An add-on for Plone]: Add-on test for Plone

--> Do you want me to initialze a GIT repository in your new package? (y/n) [y]: n

--> Plone version [5.1]: 5.2

--> Python version for virtualenv [python2.7]: python3.7


git init is disabled!
Generated file structure at /home/user/plone/test/trunk/plone.app.RAKK-test

Then I uploaded my newly created sources to Subversion: svn add *, then svn commit.

With my project newly created, I added the following entries on my configuration file /opt/plone/zinstance/develop.cfg:

[sources]
plone.app.RAKK-test = svn https://192.168.1.10/svn/SVN/plone-test/trunk/plone.app.RAKK-test

[buildout]
always-accept-server-certificate = true

To rule out possible issues with certificate acceptance, I created a temporary directory called /tmp/plone-temp and set its ownership with chown -R plone_buildout:plone_group /tmp/plone-temp, then ran an SVN checkout under user plone_buildout: sudo -u plone_buildout svn checkout https://192.168.1.10/svn/SVN/plone-test/trunk/plone.app.RAKK-test. SVN indeed asked me to trust my server's certificate, to which I chose the option to trust it permanently.

Then, without Plone running, I had Buildout apply the development configuration: cd /opt/plone/zinstance, then sudo -u plone_buildout bin/buildout -c develop.cfg.

However, Buildout fails with the following error:

root@host:/opt/plone/zinstance# sudo -u plone_buildout bin/buildout -c develop.cfg
mr.developer: Queued 'plone.app.RAKK-test' for checkout.
mr.developer: Checked out 'plone.app.RAKK-test' with subversion.
Develop: '/opt/plone/zinstance/src/plone.app.RAKK-test'
error in plone.app.RAKK-test setup command: ("EntryPoint must be in 'name=module:attrs [extras]' format", 'update_locale = plone.app.RAKK-test.locales.update:update_locale')
While:
  Installing.
  Processing develop directory '/opt/plone/zinstance/src/plone.app.RAKK-test'.

An internal error occurred due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
  File "/opt/plone/zinstance/lib/python3.7/site-packages/zc/buildout/buildout.py", line 2174, in main
    getattr(buildout, command)(args)
  File "/opt/plone/zinstance/lib/python3.7/site-packages/zc/buildout/buildout.py", line 679, in install
    installed_develop_eggs = self._develop()
  File "/opt/plone/zinstance/lib/python3.7/site-packages/zc/buildout/buildout.py", line 922, in _develop
    zc.buildout.easy_install.develop(setup, dest)
  File "/opt/plone/zinstance/lib/python3.7/site-packages/zc/buildout/easy_install.py", line 1100, in develop
    call_subprocess(args)
  File "/opt/plone/zinstance/lib/python3.7/site-packages/zc/buildout/easy_install.py", line 166, in call_subprocess
    % repr(args)[1:-1])
Exception: Failed to run command:
'/opt/plone/zinstance/bin/python3.7', '/tmp/tmp7pwev_7c', '-q', 'develop', '-mN', '-d', '/opt/plone/zinstance/develop-eggs/tmpd785ylqtbuild'

This does not look like a bug, because I got the same error after installing Plone 5.1.6 on a separate directory, which uses Python 2.7.

However, after reading and re-reading the documentation many times, I just can't figure out what am I missing or why Plone is not fetching my add-on. Would it be possible for anyone to help me sort this out, or at least give me some pointers to something I might be missing?

I have already tried the following:

From this thread here, ensuring that the Python setuptools package is installed. It is installed both under my system-wide instances of Python 2.7 and Python 3.7.

This is what I'm going to try:

From the same thread about checking setuptools, there is a chance that Plone packages must not have hyphens in the name. I'm going to try recreating the package with a hyphen-less name.

Plone does not checkout a development addon over SVN, buildout fails when applying develop.cfg - what am I doing wrong?