merge revision(s) fbbc37dc1d5b329777e6d9716118db528ab70730: [Backport #17802]

	test/drb/test_drb.rb: Specify the host of DRbServer

	to try fixing the following error.

	http://rubyci.s3.amazonaws.com/opensuseleap/ruby-master/log/20210407T063004Z.log.html.gz
	```
	[  605/21105] DRbTests::TestDRbSSLAry#test_06_next/home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/lib/drb/drb.rb:1138:in `method_missing': undefined method `regist' for [1, 2, "III", 4, "five", 6]:Array (NoMethodError)
		from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/lib/drb/extserv.rb:21:in `block in initialize'
		from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/.ext/common/monitor.rb:202:in `synchronize'
		from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/.ext/common/monitor.rb:202:in `mon_synchronize'
		from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/lib/drb/extserv.rb:20:in `initialize'
		from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/test/drb/ut_array_drbssl.rb:35:in `new'
		from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/test/drb/ut_array_drbssl.rb:35:in `<main>'
	 = 100.05 s
	```

	Here is my analysis:
	The test of drb used both `druby://:0` and `druby://localhost:0` for
	DRbServer. However, the former listens on IPv4, and the latter does on
	IPv6, depending on environments. The port 0 is automatically assigned,
	but sometimes the same port is used to both because they are different
	protocols (IPv4 and IPv6). In this case, their URIs are resolved to the
	completely same one (`druby://localhost:port`), which confuses the
	method `DRb.here?` which determines the DRbObject is remote or local.

	This changeset uses `druby://localhost:0` consistently.
	---
	 test/drb/test_drb.rb    | 4 ++--
	 test/drb/test_drbssl.rb | 2 +-
	 2 files changed, 3 insertions(+), 3 deletions(-)

3 files changed, 4 insertions, 4 deletions

diff --git a/test/drb/test_drb.rb b/test/drb/test_drb.rb
index 47b2966ae2..6d7b10e347 100644
--- a/test/drb/test_drb.rb
+++ b/test/drb/test_drb.rb
@@ -323,7 +323,7 @@ class TestDRbAnyToS < Test::Unit::TestCase
   end
 
   def test_any_to_s
-    server = DRb::DRbServer.new('druby://:0')
+    server = DRb::DRbServer.new('druby://localhost:0')
     server.singleton_class.send(:public, :any_to_s)
     assert_equal("foo:String", server.any_to_s("foo"))
     assert_match(/\A#<DRbTests::TestDRbAnyToS::BO:0x[0-9a-f]+>\z/, server.any_to_s(BO.new))
@@ -335,7 +335,7 @@ end
 
 class TestDRbTCP < Test::Unit::TestCase
   def test_immediate_close
-    server = DRb::DRbServer.new('druby://:0')
+    server = DRb::DRbServer.new('druby://localhost:0')
     host, port, = DRb::DRbTCPSocket.send(:parse_uri, server.uri)
     socket = TCPSocket.open host, port
     socket.shutdown
diff --git a/test/drb/test_drbssl.rb b/test/drb/test_drbssl.rb
index 1763b38448..0254c7ab50 100644
--- a/test/drb/test_drbssl.rb
+++ b/test/drb/test_drbssl.rb
@@ -34,7 +34,7 @@ class DRbSSLService < DRbService
         [ ["C","JP"], ["O","Foo.DRuby.Org"], ["CN", "Sample"] ]
     end
 
-    @server = DRb::DRbServer.new('drbssl://:0', manager, config)
+    @server = DRb::DRbServer.new('drbssl://localhost:0', manager, config)
   end
 end
 
diff --git a/version.h b/version.h
index 4e51660501..41f7a51c79 100644
--- a/version.h
+++ b/version.h
@@ -12,7 +12,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 2
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 65
+#define RUBY_PATCHLEVEL 66
 
 #define RUBY_RELEASE_YEAR 2021
 #define RUBY_RELEASE_MONTH 4