[QA] win10 VFS: Sync silently failing when disk is full

[jnweiger]

Test on Win10 Pro 20H2
https://download.owncloud.com/desktop/ownCloud/testing/2.7.4-rc1.2909/win/ownCloud-2.7.4-rc1.2909.x64.msi

• fill the local disk, so that only 1MB remains free
• connect client to demo.owncloud.org in VFS mode
• double click to open the Desktop Manual.pdf (6MB)
• the PDF is opened. Okayis (somewhere windows has more space than expected)
• the desktop client reports problems, but only when explicitly opened:
  
  

Expected behaviour: the desktop client should at least file up a Notification to alert about the "pending sync" state

• when more files are requested, windows eventually fails to open them:
• the error message is misleading "Not enough space on ownCloud" -- no, the problem is locally.
  

Expected behaviour: correct error messages :-) (probably window's fault, is it?

[jnweiger]

With 250MB space free and some new files to sync down:

Where is that 238MB limit configured?