Semicolon rule incorrectly fixes trailing commas

[greglo]

Bug Report

• TSLint version: 4.0.2
• TypeScript version: 2.0.3
• Running TSLint via: CLI

TypeScript code being linted with --fix

interface ITest {
    trailingComma: string,
}

Actual behavior

A semicolon is appended instead of replacing the comma

interface ITest {
    trailingComma: string,;
}

Expected behavior

The comma is replaced with a semicolon

interface ITest {
    trailingComma: string;
}

See failing test case: greglo@66e7022

[rjmunro]

Also, if every time you run the fix again, you get another ;:

So:

interface ITest {
    trailingComma: string,;;
}

Then:

interface ITest {
    trailingComma: string,;;;
}

etc.

I would expect fixes to be idempotent.