Steps to reproduce the issue

1. When you have a package installed that didn't have a changelogurl set in the manifest file and you upgrade that package with a version that does have a changelogurl set in the manifest, this changelogurl is not stored in that database.
2. when you change the changelogurl in your package and install this updated package, the changelogurl is still the old one > so not updated

currently changelogurl is only set (and thus used) on newly installed packages. The changelog button is showed, but when clicked there is not url set to get the contents from (and displays an empty popup)

Expected result

changelogurl field in table #__extensions for packages should be updated to (new) changelogurl

Actual result

changelogurl field in table #__extensions for packages is not updated

System information (as much as possible)

Additional comments

workaround is to set it manually via a install script on updating the package.