[Bug] g.extension module does not update modules.xml file if prefix parametr argument base addons custom directory path is used

[tmszi]

Describe the bug

g.extension module does not update modules.xml file if prefix param argument base addons custom directory path is used. Modules XML file is used by wxGUI Tools tree Addons node.

To reproduce

1. Install some addon into custom base addons dir path (use prefix=/tmp/addons param arg) g.extension wx.metadata operation=add prefix=/tmp/addons
2. See warning messages:

GRASS nc_basic_spm_grass7/temp:~ > g.extension wx.metadata operation=add prefix=/tmp/addons
Enumerating objects: 1, done.
Counting objects: 100% (1/1), done.
Writing objects: 100% (1/1), done.
Total 1 (delta 0), reused 1 (delta 0), pack-reused 0 (from 0)
Fetching <wx.metadata> from <https://github.com/OSGeo/grass-addons/> (be
patient)...
Enumerating objects: 1, done.
Counting objects: 100% (1/1), done.
Writing objects: 100% (1/1), done.
Total 1 (delta 0), reused 1 (delta 0), pack-reused 0 (from 0)
remote: Enumerating objects: 104, done.
remote: Counting objects: 100% (58/58), done.
remote: Compressing objects: 100% (51/51), done.
remote: Total 104 (delta 13), reused 7 (delta 7), pack-reused 46 (from 3)
Receiving objects: 100% (104/104), 246.06 KiB | 1.94 MiB/s, done.
Resolving deltas: 100% (17/17), done.
Already on 'grass8'
Your branch is up to date with 'origin/grass8'.
Compiling...
Installing...
/home/tomas/.grass8/addons
Updating extensions metadata file...
Updating extension modules metadata file...
Enumerating objects: 1, done.
Counting objects: 100% (1/1), done.
Writing objects: 100% (1/1), done.
Total 1 (delta 0), reused 1 (delta 0), pack-reused 0 (from 0)
WARNING: No metadata available for module 'db.csw.harvest': Unable to fetch
         interface description for command '<db.csw.harvest>'.

         Details: <Cannot find the executable db.csw.harvest>
WARNING: No metadata available for module 'r.info.iso': Unable to fetch
         interface description for command '<r.info.iso>'.

         Details: <Cannot find the executable r.info.iso>
WARNING: No metadata available for module 't.info.iso': Unable to fetch
         interface description for command '<t.info.iso>'.

         Details: <Cannot find the executable t.info.iso>
WARNING: No metadata available for module 'g.gui.cswbrowser': Unable to
         fetch interface description for command '<g.gui.cswbrowser>'.

         Details: <Cannot find the executable g.gui.cswbrowser>
WARNING: No metadata available for module 'm.csw.update': Unable to fetch
         interface description for command '<m.csw.update>'.

         Details: <Cannot find the executable m.csw.update>
WARNING: No metadata available for module 'v.info.iso': Unable to fetch
         interface description for command '<v.info.iso>'.

         Details: <Cannot find the executable v.info.iso>
WARNING: No metadata available for module 'db.csw.admin': Unable to fetch
         interface description for command '<db.csw.admin>'.

         Details: <Cannot find the executable db.csw.admin>
WARNING: No metadata available for module 'g.gui.metadata': Unable to fetch
         interface description for command '<g.gui.metadata>'.

         Details: <Cannot find the executable g.gui.metadata>
WARNING: No metadata available for module 'db.csw.run': Unable to fetch
         interface description for command '<db.csw.run>'.

         Details: <Cannot find the executable db.csw.run>
Installation of <wx.metadata> successfully finished

modules.xml file is empty:

GRASS nc_basic_spm_grass7/temp:~ > cat /tmp/addons/modules.xml 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE task SYSTEM "grass-addons.dtd">
<addons version="8">
</addons>

wxGUI Tools tree Addons node does not exist (if base addons custom dir path is used export GRASS_ADDON_BASE=/tmp/addons

Expected behavior

g.extension module should update modules.xml file if prefix param argument base addons custom directory path is used. And wxGUI Tools tree Addons node should exist and contains installed addons, when GRASS_ADDON_BASE ENV pointing to this base addons addons custom dir (e.g. /tmp/addons).

System description

• Operating System: all
• GRASS version: all