Only check out a Redis connection if necessary

In Sidekiq 7, calls to `Sidekiq.redis` checks out a connection from an
internal connection pool instead of the connection pool used by the
job processors. If a connection is checked out but not used, it's
possible that the heartbeat thread won't keep the connection alive
before the Redis server client timeout.

To avoid this, update the checks to return earlier if the Redis
connection is not needed.

This might help reduce intermittent `Broken pipe` errors as reported
in redis-rb/redis-client#119.

lib/sidekiq/cron/job.rb

@@ -21,13 +21,15 @@ class Job
 
       # Crucial part of whole enqueuing job.
       def should_enque? time
+        return false unless status == "enabled"
+        return false unless not_past_scheduled_time?(time)
+        return false unless not_enqueued_after?(time)
+
         enqueue = Sidekiq.redis do |conn|
-          status == "enabled" &&
-            not_past_scheduled_time?(time) &&
-            not_enqueued_after?(time) &&
-            conn.zadd(job_enqueued_key, formatted_enqueue_time(time), formatted_last_time(time))
+          conn.zadd(job_enqueued_key, formatted_enqueue_time(time), formatted_last_time(time))
         end
-        enqueue == true || enqueue == 1
+
+        enqueue == 1
       end
 
       # Remove previous information about run times,
@@ -239,12 +241,11 @@ def self.count
       def self.find name
         # If name is hash try to get name from it.
         name = name[:name] || name['name'] if name.is_a?(Hash)
+        return unless exists? name
 
         output = nil
         Sidekiq.redis do |conn|
-          if exists? name
-            output = Job.new conn.hgetall( redis_key(name) )
-          end
+          output = Job.new conn.hgetall( redis_key(name) )
         end
         output if output && output.valid?
       end