2.38.1:
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    * Fix count_plugin_upgrades():
      Don't get plugin name from path, as event and sidebar plugins
      may share their path; strip instance from name instead.

2.38:
-----
    * Add function to count upgradeable plugins.
    * Add upgrade notifier to plugin upgrade button.
    * Add 'backend_plugins_upgradecount' hook and
      language constants for a dashboard upgrade
      notification.

2.37.6:
-------
    * Fix wrong caching of plugin lists regardless of type.

2.37.5:
-------
    * Fix missing reset to default after dropping netmirror.

2.37.4:
-------
    * Drop netmirror, set mirror to default if it was set to netmirror.

2.37.3:
-------
    * Change mirror order (new default: github)