Don't overwrite existing file contents.

We need to truncate if file already exists.

Author: grokys

src/GitHub.VisualStudio/Services/UsageService.cs

@@ -110,7 +110,7 @@ async Task<string> ReadAllTextAsync(string path)
 
         async Task WriteAllTextAsync(string path, string text)
         {
-            using (var s = File.OpenWrite(path))
+            using (var s = new FileStream(path, FileMode.Create))
             using (var w = new StreamWriter(s, Encoding.UTF8))
             {
                 await w.WriteAsync(text);