Question about Admin/Plugins/Manage Plugins display

[W. Martin Borgert]

Hi,

when I install a plugin locally in one Trac instance (upload of
an egg file), the plugin is displayed correctly:

▶ Trac 0.11.5
▼ TracFooPlugin 1.2.3
Trac Plugin to do foo
Author: Foo author
Home page: http://trac-hacks.org/wiki/TracFoo
License: BSD

Component Enabled
TracFooPluginBar □

When I install the plugin globally in the Python environment,
therefore visible to all Trac instances, the plugin is displayed
under some arbitrary Python package, that is not even related to
Trac, e.g.:

▶ Trac 0.11.5
▼ Django 1.1.1
A high-level Python Web framework that encourages rapid...
Author: found...@djangoproject.com
Home page: http://www.djangoproject.com/
License: ...

Component Enabled
TracFooPluginBar □

What's wrong, why, and howto repair it? Many thanks in advance
for any insight!