[False positive] no-async-without-await and abstract methods

[feimosi]

Bug Report

• TSLint version: tslint@5.18.0
• TypeScript version: typescript@3.5.2
• Running TSLint via: CLI and VSCode

Reproduction using TSLint Playground

I couldn't reproduce it in the Playground, however even invalid code is not detected by this rule what apparently means the rule is not present there at all (?)
TSLint Playground

TypeScript code being linted

export abstract class SomeService<T> {
  protected readonly abstract repository: Repository<T>;

  protected abstract async falsePositive(id: number): Promise<T | null>;

  public async truePositive() { /* */ }
}

with tslint.json configuration:

{
  "extends": [
    "tslint:all",
    "tslint-config-standard",
    "tslint-config-airbnb-base"
  ],
  "rules": {
    "no-async-without-await": true,
	"...": "..."
  }
}

Actual behavior

Treats abstract methods as an error

Expected behavior

Should ignore abstract methods because they don't have a body

[danielrentz]

Same for overloaded functions/methods, as described in #4776