output filename clash handling?

[andhya]

It seems like when a .db file of the same name already exists, the command runs to completion without writing any output file?

I've been trying to explore the data in the sse_powercuts repo and so I've just been making minor changes to how I run it each time, and getting increasingly surprised/confused/frustrated when the result seems to be the same - until I looked at the timestamp of the file and saw - aha! - it actually hasn't changed at all!

It's very possible I've just misunderstood something and am using it wrong but that seems to be the behaviour I'm seeing?