In idiomatically written Rust you will never obtain an exception/panic (unless there is a bug), and exceptions are not used for control flow. This is not the case in Java or C++ or many other languages.
/// The compiler currently unwinds with a special sentinel value to abort
/// compilation on fatal errors. This function catches that sentinel and turns
/// the panic into a `Result` instead.
There's another example in src/tools/rustfmt/src/lib.rs, in format_snippet, where panics apparently are just suppressed.
I expect application servers for Rust to handle panics in a similar way: abort a specific request, but not terminate the whole process.