moving directories with -keep-parent does not work anymore due to changes by Google

[shekvl]

Moving directories with -keep-parent does not work anymore despite still being documented (the option is currently ignored, so the directory is simply moved to a new parent). The reason is that starting from 2020 directories cannot have more than one parent: https://developers.google.com/drive/api/v2/multi-parenting

Maybe it makes sense to remove this option and update the documentation. Handling shortcuts as Google suggests could be a nice addition as well, but this probably has to be implemented as a different command.