Windows: Allow `gvfs upgrade` on pre-RS4

Background

gvfs upgrade is not supported on pre-RS4 versions of Windows because ProjFS does not ship as part of Windows, and we want to make sure that gvfs upgrade does not break other tool(s) that depend on the installed version of ProjFS.

Current status of non-inbox ProjFS

With the recent upgrade to ProjFS 2019.411.1 there are no plans for future upgrades the ProjFS that is shipped with VFS4G. Once pre-RS4 users have upgraded to this version chances are that we could allow them to use gvfs upgrade because VFS4G usually won’t be changing the version of ProjFS that’s installed.

Proposed changes

• Provide VFS4G with a way to discover what version of ProjFS is packaged with VFS4G. A few options include:

  • Update the new anonymous endpoint to provide ProjFS version data
  • Include the version data in the nuget package manifest

• When VFS4G is running on a pre-RS4 version of Windows, it can check if the installed version of ProjFS matches the version that’s bundled with the upgrade. If the versions match then gvfs upgrade would be allowed to proceed

• gvfs upgrade would continue to be disallowed if a non-inbox version is installed on an RS4+ version of Windows.

Start by tracing the gvfs upgrade handling and the existing ProjFS version checks on pre-RS4 and RS4+ Windows. Review the proposed endpoint or NuGet manifest version sources, then verify that matching bundled and installed versions allow upgrades while non-inbox ProjFS remains blocked on RS4+.