Steps to reproduce the issue

• J4.0 current nightly build
• Install a module that has no changelogurl in it's manifest or update-XML.

E.g. this one for Joomla 3: https://snapshots.ghsvs.de/updates/joomla/mod_administratorlinkghsvs/mod_administratorlinkghsvs_2015.12.28.zip

• Then install the same module built for Joomla 4 following the docs on https://docs.joomla.org/Adding_changelog_to_your_manifest_file.

E.g. this one for Joomla 4: https://github.com/GHSVS-de/mod_administratorlinkghsvs/archive/2020.05.23.zip

Expected result

• After update entry in changelogurl field of table #__extensions because it's in the new manifest file.
  https://github.com/GHSVS-de/mod_administratorlinkghsvs/blob/2020.05.23/mod_administratorlinkghsvs.xml#L17

Actual result

• changelogurl field empty.
• Therefore Changelog feature in extensions > update will not work with next release.
• Only the headline and the new version will be displayed in modal.
• the logic will stop working here https://github.com/joomla/joomla-cms/blob/4.0-dev/administrator/components/com_installer/src/Model/ManageModel.php#L457

Addition

• If you make a fresh install of the Joomla 4 module changelogurl is filled in database.