Delete cfgFile before renaming it on Windows

main.go

@@ -328,6 +328,13 @@ func saveConfigLoop(cfgFile string) {
 			continue
 		}
 
+		if runtime.GOOS == "windows" {
+			err := os.Remove(cfgFile)
+			if err != nil && !os.IsNotExist(err) {
+				warnln(err)
+			}
+		}
+
 		err = os.Rename(cfgFile+".tmp", cfgFile)
 		if err != nil {
 			warnln(err)