cmd/tailscale/cli: don't force an interactive login on --reset.

Fixes #1778

Signed-off-by: David Anderson <danderson@tailscale.com>

cmd/tailscale/cli/up.go

@@ -435,8 +435,10 @@ func runUp(ctx context.Context, args []string) error {
 		}
 
 		bc.Start(opts)
+		if upArgs.forceReauth {
 			startLoginInteractive()
 		}
+	}
 
 	select {
 	case <-startingOrRunning: