Allow schemeless clone URLs

tools/SetupFlow/DevHome.SetupFlow/ViewModels/AddRepoViewModel.cs

@@ -1181,25 +1181,32 @@ public void AddOrRemoveRepository(string accountName, IList<object> repositories
     /// <remarks>If the url is not valid this method sets UrlParsingError and ShouldShowUrlError to the correct values.</remarks>
     private void ValidateUriAndChangeUiIfBad(string url, out Uri uri)
     {
-        uri = null;
-
         // If the url isn't valid don't bother finding a provider.
-        if (!Uri.IsWellFormedUriString(url, UriKind.Absolute) ||
-            !Uri.TryCreate(url, UriKind.RelativeOrAbsolute, out uri))
+        if (!Uri.TryCreate(url, UriKind.RelativeOrAbsolute, out uri))
         {
             UrlParsingError = _stringResource.GetLocalized(StringResourceKey.UrlValidationBadUrl);
             ShouldShowUrlError = true;
             return;
         }
 
         // If user entered a relative Uri put it into a UriBuilder to turn it into an
-        // absolute Uri.  UriBuilder prepends the https scheme
+        // absolute Uri. UriBuilder prepends the specified scheme.
         if (!uri.IsAbsoluteUri)
         {
             try
             {
-                var uriBuilder = new UriBuilder(uri.OriginalString);
-                uriBuilder.Port = -1;
+                var uriBuilder = new UriBuilder(Uri.UriSchemeHttps, uri.OriginalString)
+                {
+                    Port = -1,
+                };
+
+                if (!Uri.IsWellFormedUriString(uriBuilder.Uri.OriginalString, UriKind.Absolute))
+                {
+                    UrlParsingError = _stringResource.GetLocalized(StringResourceKey.UrlValidationBadUrl);
+                    ShouldShowUrlError = true;
+                    return;
+                }
+
                 uri = uriBuilder.Uri;
             }
             catch (Exception e)