merge revision(s) e0dd072978e6c2c8180e75617e7ee37830caefa3,85f99f4b715a5954124d5014002c16652995b128:

	Fix errors when XDG_CONFIG_HOME points to non-writable directory

	`$HOME/.config` is not writable on CI
	because I think tests should not corrupt user's data.

	And GitHub Actions CI sets `XDG_CONFIG_HOME`
	since `Version: 20210309.1`.

	https://github.com/ruby/actions/runs/2130811016?check_suite_focus=true#step:16:301
	```
	Errno::EACCES: Permission denied @ dir_s_mkdir - /home/runner/.config/irb
	```
	---
	 test/irb/test_cmd.rb | 2 ++
	 1 file changed, 2 insertions(+)

	Try to fix errors in TestIRB::TestHistory too

	https://github.com/ruby/actions/runs/2137935523?check_suite_focus=true#step:9:562
	```
	  1) Error:
	TestIRB::TestHistory#test_history_concurrent_use:
	Errno::EACCES: Permission denied @ dir_s_mkdir - /home/runner/.config/irb
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:253:in `mkdir'
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:253:in `fu_mkdir'
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:231:in `block (2 levels) in mkdir_p'
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:229:in `reverse_each'
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:229:in `block in mkdir_p'
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:211:in `each'
	    /home/runner/work/actions/actions/ruby/lib/fileutils.rb:211:in `mkdir_p'
	    /home/runner/work/actions/actions/ruby/lib/irb/init.rb:355:in `rc_file_generators'
	    /home/runner/work/actions/actions/ruby/lib/irb/init.rb:330:in `rc_file'
	    /home/runner/work/actions/actions/ruby/test/irb/test_history.rb:170:in `block in assert_history'
	    /home/runner/work/actions/actions/ruby/lib/tmpdir.rb:96:in `mktmpdir'
	    /home/runner/work/actions/actions/ruby/test/irb/test_history.rb:168:in `assert_history'
	    /home/runner/work/actions/actions/ruby/test/irb/test_history.rb:133:in `test_history_concurrent_use'
	```
	---
	 test/irb/test_history.rb | 2 ++
	 1 file changed, 2 insertions(+)

3 files changed, 5 insertions, 1 deletions

diff --git a/test/irb/test_cmd.rb b/test/irb/test_cmd.rb
index bb33f535b6..d0f1ac645c 100644
--- a/test/irb/test_cmd.rb
+++ b/test/irb/test_cmd.rb
@@ -17,12 +17,14 @@ module TestIRB
       Dir.chdir(@tmpdir)
       @home_backup = ENV["HOME"]
       ENV["HOME"] = @tmpdir
+      @xdg_config_home_backup = ENV.delete("XDG_CONFIG_HOME")
       @default_encoding = [Encoding.default_external, Encoding.default_internal]
       @stdio_encodings = [STDIN, STDOUT, STDERR].map {|io| [io.external_encoding, io.internal_encoding] }
       IRB.instance_variable_get(:@CONF).clear
     end
 
     def teardown
+      ENV["XDG_CONFIG_HOME"] = @xdg_config_home_backup
       ENV["HOME"] = @home_backup
       Dir.chdir(@pwd)
       FileUtils.rm_rf(@tmpdir)
diff --git a/test/irb/test_history.rb b/test/irb/test_history.rb
index 392a6afa9a..1ba4d2e515 100644
--- a/test/irb/test_history.rb
+++ b/test/irb/test_history.rb
@@ -132,6 +132,7 @@ module TestIRB
     def assert_history(expected_history, initial_irb_history, input)
       backup_verbose, $VERBOSE = $VERBOSE, nil
       backup_home = ENV["HOME"]
+      backup_xdg_config_home = ENV.delete("XDG_CONFIG_HOME")
       IRB.conf[:LC_MESSAGES] = IRB::Locale.new
       actual_history = nil
       Dir.mktmpdir("test_irb_history_#{$$}") do |tmpdir|
@@ -160,6 +161,7 @@ module TestIRB
     ensure
       $VERBOSE = backup_verbose
       ENV["HOME"] = backup_home
+      ENV["XDG_CONFIG_HOME"] = backup_xdg_config_home
     end
 
     def with_temp_stdio
diff --git a/version.h b/version.h
index 0c5807b1a6..21f37b93dd 100644
--- a/version.h
+++ b/version.h
@@ -2,7 +2,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 3
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 171
+#define RUBY_PATCHLEVEL 172
 
 #define RUBY_RELEASE_YEAR 2021
 #define RUBY_RELEASE_MONTH 3