The nice thing about Bash which can obviously not be said about Python is that Bash scripts will keep working (assuming whatever they call is also there of course) since Bash goes out of its way to preserve backwards compatibility. Considering its legacy, Bash can run scripts more than a decade before Python even existed.

The only other scripting language i know of that has similar backwards compatibility is Tcl. Perhaps Perl too (ignoring Perl 6 that was renamed to something else again due to it being practically a different language).