[Bug] OSGeo4W grass-dev package can't launch since July 7

[echoix]

Describe the bug

I kept my OSGeo4W installation up to date, but didn't really launch GRASS on Windows for a while. The latest nightly didn't launch, and opening grass85 in the OSGeo4W Shell shows a traceback in the find_grass_python_package() function. After reverting to a previous version, then downloading multiple old nightlies from https://download.osgeo.org/osgeo4w/v2/snapshots/20250830-001051/x86_64/release/grass-dev/?C=M&O=D, then bisecting when it stopped working, (with tips from the file's history https://github.com/OSGeo/grass/commits/main/lib/init), the problem was introduced in #5933 with FHS related changes

To reproduce

1. Install any grass-dev version from OSGeo4W installer on Windows.
2. Launch "GRASS GIS 8.5.0dev" (the shortcut still uses GRASS GIS)
3. Command appears and closes, as there's an error.
4. Open the "OSGeo4W shell"
5. Type grass85 and press the enter key to start grass85
6. See the traceback

Expected behavior

Have grass 8.5 launch on Windows.

Screenshots

System description

• Operating System: Windows 11 24H2
• GRASS version: 8.5
• details about further software components: Not working

Additional context

I thought that #6239 might have been the cause, but no. Probably the collaborator was already hitting this problem.

See the last two screenshots. The problem is that the path replaced in the file has traces to the source or installation directory on the build server, not the installed path.

The fix might in part come from us, but probably need some changes in the OSGeo4W build scripts, where these kind of path overrides on installation are done. The current file is at https://github.com/jef-n/OSGeo4W/blob/d183e43f08609ddb6ef9d3644c89392922f3a1c0/src/grass-dev/osgeo4w/package.sh

[echoix]

@jef-n Do you have an idea on what changes on the OSGeo4W side would be the best here? There's always the mswindows/osgeo4w/env.bat.tmpl file that we could adapt to add the env var, but the build server directory will still appear in user installs as the fallback, so it's only a partial fix. With the new available variables from the PR #5933, in particular this file https://github.com/OSGeo/grass/pull/5933/files#diff-647be4ef599868c33f2f69f0d899f79f0aee8d75d1db74f523268c1ac94cddf7, is there something better that can be done as the OSGeo4W integration?

[echoix]

Doing a search in the OSGeo4W repo, I think that QGIS too will need to have a change when they'll want to use GRSS 8.5 (at least for the OSGeo4W files), as they add some env vars in some launch files to be able to use GRASS.

[echoix]

I wanted to try again now that #6391 and similar PRs were merged, but the latest grass-dev nightly package built was on Sept 23, 2025, with build 609 for commit 2aa4836. Something must be stuck.

[nilason]

I wanted to try again now that #6391 and similar PRs were merged, but the latest grass-dev nightly package built was on Sept 23, 2025, with build 609 for commit 2aa4836. Something must be stuck.

https://wingrass.fsv.cvut.cz/grass85/osgeo4w/

[echoix]

I wanted to see specifically osgeo4w, since grass-dev isn’t actually launching since July

[echoix]

New OSGeo4W builds have been made and available, and now grass 8.5dev opens on Windows successfully. So, resolved.