Presets opened from relation editor need to pass selection to preset_link

[skyper]

This is similar or even related with #18992.

What steps will reproduce the problem?

1. Open a PTv2 route relation in relation editor
2. Select several PTv2 route relations
3. In relation editor click on a link to a preset which itself includes a <preset_link> (I used my new Public Transport GTFS preset)
4. Click on the preset link in the preset.

What is the expected result?

I am still editing only the relation from the relation editor

What happens instead?

The main selection from MapView is used and I am editing a bunch of relations

Please provide any additional information below. Attach a screenshot if possible.

Problem is that the selection is not passed through with <preset_link>.
I set this to critical as user might not even notice the different selection and break data.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-06-14 22:59:08 +0200 (Sun, 14 Jun 2020)
Revision:16645
Build-Date:2020-06-15 01:30:49
URL:https://josm.openstreetmap.de/svn/trunk

[simon04]

In 16699/josm:

fix #19392 - Presets opened from relation editor need to pass selection to preset_link

[GerdP]

This introduced NPEs, see #20044