Compiler reports `used before assigned` after `try...finally` block

[HerringtonDarkholme]

TypeScript Version: nightly (2.1.0-dev.20161112), --stricNullChecks

Note: this code compiles under 2.0.9

Code

// @strictNullChecks
declare function openFile(): void
declare function closeFile(): void
declare function someOperation(): {}

var result: {}
openFile()
try {
  result = someOperation()
} finally {
  closeFile()
}

result // error here

Expected behavior:

The code should compile. As #9260 (comment) goes, the try ... finally ... is a grammatical construct. If someOperation breaks the control flow, code after try-finally block will not be reachable. So result after block must be assigned.

Actual behavior:

Error as commented.

Related issues:
I have found a lot flow related issues. But they are more about closure/function declaration than try-catch-finally. So I think this is not a duplicate.