Werk #11900: Avoid duplicate display for extension packages

Component	Core & setup
Title	Avoid duplicate display for extension packages
Date	Dec 22, 2020
Level	Trivial Change
Class	Bug Fix
Compatibility	Compatible - no manual interaction needed
Checkmk versions & editions	2.1.0b1 Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk MSP (CME) 2.0.0b4 Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk MSP (CME)

This fixes the case where mkp find shows the same file under multiple categories.

This also fixes the same error in the UI for the "Extension packages" display.

To the list of all Werks