Language detection is ignoring file extension for untitled files

Maybe this isn't the best way to do it, but I open this untitled file with an explicit .md extension using the extension API: ``` const doc = await vscode.workspace.openTextDocument(vscode.Uri.from({ scheme: 'untitled', path: `Inspect ${basename(uri.path.replace(/\.png$/, ''))}.md` })) ``` Notice in the below gif that markdown is correctly selected initially, but then the language detection incorrectly changes it to Dart. The fact that it thinks it's Dart is a little weird but expected in a way since it's using ML, what's not expected it to overwrite an already explicitly set language mode.  Also saw this happen with Rust if that's of any use.