Update paths on directory rename loses file casing

[mjbvz]

TypeScript Version: 2.9.2

Search Terms:

• update import paths
• rename directory
• getEditsForFileRename

Code
For a project:

index.ts

import { abc } from './sub/aBc';
console.log(abc)

sub/aBc.ts

export const abc = 123;

1. Rename sub to sub2

Expected behavior:
index.ts becomes:

import { abc } from './sub2/aBc';
console.log(abc)

Actual behavior:
File casing on aBc lost. index.ts becomes:

import { abc } from './sub2/abc';
console.log(abc)

[mjbvz]

I'm going to add a workaround for this on the VS Code side too since we won't be picking up TS 3.0 this iteration