Joomla's discover functionality adds, without installing, Templates to Extensions table with enabled=1, which makes its Module Positions visible in Module Manager, while the template has not been installed.

Steps to reproduce the issue

Create a new front-end template with some example module positions:
/templates/example/templateDetails.xml

<?xml version="1.0" encoding="utf-8"?>
<extension version="3.6" type="template" client="site">
    <name>EXamPLe</name>
    <version>1.0</version>
    <creationDate>4 November 2016</creationDate>
    <author>Peter Martin</author>
    <positions>
        <position>aaa</position>
        <position>bbb</position>
        <position>ccc</position>
    </positions>
</extension>

In Joomla back-end: Extensions > Manage > Discover
Do not install the template.

Go to Extensions > Modules > create /edit a module,
and notice that the Module Positions of the Template that is not installed, are available.

Expected result

Module Positions in Templates that are not installed, should not be available in the Module Manager

Actual result

Joomla's "Discover" adds discovered (but uninstalled) Templates to the Extension database table, and sets enabled = 1.

The enabled field is "1" by default. IMHO that should be "0" by default.