bug#19065: dd design bug

[bt]

The following undocumented behavior of dd is (IMO) a design flaw.

If dd is used to copy one partition to another, as in

#dd if=/dev/sda3 of=/dev/sdb3 ...

and if in fact sdb3 does not exist, then dd will overwrite the first part of
an existing partition *sda1*. 

It doesn't make sense that if the "of=" device doesn't exist, then another
pre-existing device, not mentioned in the command line, is overwritten.
Several websites have incorrect information about the behavior of dd in this
situation. 
At the very least, this should be documented--maybe I'm missing something, but 
didn't see it in the man pages or the texinfo manual.

Thanks,B. Titus