Option to create ancestors of destination, like "mkdir -p

[henri]

> I agree with everyone else that it would be incredibly useful for rsync to
> either adopt such behaviour by default (assuming always doing 'mkdir -p' isn't
> harmful in any way), or have a tunable to enable it.

I also agree the suggested behavior makes a lot of sense and I think it is a good idea. 

However, some deployments may rely upon the current behavior.  As an example, a setup may rely on rsync failing if a file system is not mounted.  In such a situation, it is worth contemplating whether you would you want rsync to generate the mount point and any subdirectories, specified for this rsync. 

I personally think that such checks should be external from rsync. However, changing the current default behavior has the potential to create problems on setups which may rely on the current default behavior.

I recommend the consideration of potential problems which could occur if the deployed setups are dependent on the current rsync behavior and that default behavior changes. Then based upon the severity of these potential problems move ahead or delay the change to a major revision change?

My 2ç