BUG #18245: pg_restore accepts same output file name as input file name

The following bug has been logged on the website:

Bug reference:      18245
Logged by:          Mohammad Al Zouabi
Email address:      mb.alzouabi@gmail.com
PostgreSQL version: 14.10
Operating system:   macOS
Description:

Please let it fail when the user passes the same name for the output as the
input. 

I just lost a very important .tar file because I forgot to replace .tar with
.sql.

Thanks!