Resque can't cleanup heartbeats when it's killed before calling register_worker

[mtsmfm]

Currently, Resque::DataStore::HEARTBEAT_KEY and :workers are registered independently.
If a worker is killed in

resque/lib/resque/worker.rb

Lines 366 to 367 in be71bd1

	prune_dead_workers
	run_hook :before_first_fork

, Resque::DataStore::HEARTBEAT_KEY is registered but :workers isn't.

Resque::Worker#prune_dead_workers assumes Worker.all contains such a worker but they're missed.

resque/lib/resque/worker.rb

Line 602 in be71bd1

all_workers = Worker.all

Here's an example to reproduce this problem:

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'

  gem 'resque', '2.0.0'
  gem 'rspec', require: 'rspec/autorun'
end

Resque.redis = 'redis:6379'
Resque.redis.redis.flushall

RSpec.describe do
  it do
    Process.fork do
      Resque.before_first_fork do
        while Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY) == 0
          sleep 0.1
        end

        Process.kill(:KILL, Process.pid)
      end

      worker = Resque::Worker.new('*')
      worker.prepare
      worker.work
    end

    Process.waitall

    expect(Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY)).to eq 1
    expect(Resque.redis.smembers(:workers)).to eq []

    expect {
      worker = Resque::Worker.new('*')
      worker.prune_dead_workers
    }.to change { Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY) }.from(1).to(0)
  end
end

$ ruby foo.rb
F

Failures:

  1) is expected to change `Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY)` from 1 to 0
     Failure/Error:
       expect {
         worker = Resque::Worker.new('*')
         worker.prune_dead_workers
       }.to change { Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY) }.from(1).to(0)
     
       expected `Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY)` to have changed from 1 to 0, but did not change
     # foo.rb:34:in `block (2 levels) in <main>'

Finished in 0.1311 seconds (files took 0.06291 seconds to load)
1 example, 1 failure

Failed examples:

rspec foo.rb:14 # is expected to change `Resque.redis.hlen(Resque::DataStore::HEARTBEAT_KEY)` from 1 to 0