Revert "Fix potential hang when joining threads."

This reverts commit 13f8521c630a15c87398dee0763e95f59c032a94.

http://rubyci.s3.amazonaws.com/solaris11-gcc/ruby-master/log/20210727T230009Z.fail.html.gz
http://rubyci.s3.amazonaws.com/solaris11-sunc/ruby-master/log/20210728T000009Z.fail.html.gz

This revert is to confirm whether the commit is the cause.
If the failures consistently occur after this revert, I'll
reintroduce the commit.

2 files changed, 2 insertions, 28 deletions

diff --git a/test/fiber/scheduler.rb b/test/fiber/scheduler.rb
index 2785561000..af64e4ebb6 100644
--- a/test/fiber/scheduler.rb
+++ b/test/fiber/scheduler.rb
@@ -112,10 +112,8 @@ class Scheduler
 
     self.run
   ensure
-    if @urgent
-      @urgent.each(&:close)
-      @urgent = nil
-    end
+    @urgent.each(&:close)
+    @urgent = nil
 
     @closed = true
 
@@ -242,13 +240,3 @@ class BrokenUnblockScheduler < Scheduler
     raise "Broken unblock!"
   end
 end
-
-class SleepingUnblockScheduler < Scheduler
-  # This method is invoked when the thread is exiting.
-  def unblock(blocker, fiber)
-    super
-
-    # This changes the current thread state to `THREAD_RUNNING` which causes `thread_join_sleep` to hang.
-    sleep(0.1)
-  end
-end
diff --git a/test/fiber/test_thread.rb b/test/fiber/test_thread.rb
index acc8300817..843604b5f1 100644
--- a/test/fiber/test_thread.rb
+++ b/test/fiber/test_thread.rb
@@ -66,18 +66,4 @@ class TestFiberThread < Test::Unit::TestCase
       thread.join
     end
   end
-
-  def test_thread_join_hang
-    thread = Thread.new do
-      scheduler = SleepingUnblockScheduler.new
-
-      Fiber.set_scheduler scheduler
-
-      Fiber.schedule do
-        Thread.new{sleep(0.01)}.value
-      end
-    end
-
-    thread.join
-  end
 end