To be more accurate, unwrap can be a legitimate means of error handling when used in an application, as opposed to a library. But if you're writing a library, then unwrapping rather than using Result is a surefire way to make your users hate you. :)
Aside: CPython's gdbm support is provided by libgdbm that calls exit() for you if if finds something it's not happy with (corrupted database, e.g.). O.o
In libraries one should be wary about it, and never use it if the unwrap might actually panic, but otherwise you're good to go.