ScanCode conflates `gpl-2.0` with `gpl-2.0-plus` in `license_detections`

[sschuberth]

Description

To my understanding, the license_expression field in the JSON output is supposed to contain all distinct licenses listed under reference_matches. However, in my case there are

"reference_matches": [
  // ...
  "license_expression": "public-domain AND gpl-2.0-plus AND gpl-3.0-plus",
  "license_expression": "lgpl-2.1 AND gpl-2.0 AND gpl-3.0",

but

"license_detections": [
  // ...
  "license_expression": "public-domain AND lgpl-2.1-plus AND gpl-2.0-plus AND (public-domain AND gpl-2.0-plus AND gpl-3.0-plus) AND (other-permissive AND other-copyleft) AND public-domain-disclaimer AND lgpl-2.1",

So the gpl-2.0 and gpl-3.0 license keys are missing. My guess it that they somehow get conflated into the also existing gpl-2.0-plus and gpl-3.0-plus license keys.

How To Reproduce

Using ScanCode 32.1.0, run a scan on the files mentioned at #3648.

System configuration

• What OS are you running on? Fedora Linux 30
• What version of scancode-toolkit was used to generate the scan file? 32.1.0
• What installation method was used to install/run scancode? pip