kill_spec.rb: exclude spec unstable on MinGW

like r64991, until we get helpful error logs on worker death or the
unstability is fixed.

Since mspec worker randomly dies on MinGW, maybe it should have an
option to retry worker death.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65050 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/core/thread/kill_spec.rb

@@ -2,20 +2,24 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/exit'
 
-describe "Thread#kill" do
-  it_behaves_like :thread_exit, :kill
-end
+# This spec randomly kills mspec worker like: https://ci.appveyor.com/project/ruby/ruby/builds/19473223/job/f69derxnlo09xhuj
+# TODO: Investigate the cause or at least print helpful logs, and remove this `platform_is_not` guard.
+platform_is_not :mingw do
+  describe "Thread#kill" do
+    it_behaves_like :thread_exit, :kill
+  end
 
-describe "Thread#kill!" do
-  it "needs to be reviewed for spec completeness"
-end
+  describe "Thread#kill!" do
+    it "needs to be reviewed for spec completeness"
+  end
 
-describe "Thread.kill" do
-  it "causes the given thread to exit" do
-    thread = Thread.new { sleep }
-    Thread.pass while thread.status and thread.status != "sleep"
-    Thread.kill(thread).should == thread
-    thread.join
-    thread.status.should be_false
+  describe "Thread.kill" do
+    it "causes the given thread to exit" do
+      thread = Thread.new { sleep }
+      Thread.pass while thread.status and thread.status != "sleep"
+      Thread.kill(thread).should == thread
+      thread.join
+      thread.status.should be_false
+    end
   end
 end