merge revision(s) 276f6a225d18561cbe5282b798cb4e416c66079f,95bef7b69a6fb42687a6200b338060be307259f5: [Backport #17352]

	Don't double fractional seconds when passing timezone object to
	 Time.new

	I found that fractional seconds were doubled when using the timezone
	feature of Time in Sequel's named_timezones extension (which uses
	TZInfo for the timezone object), and traced the problem to this code.

	There is no subsecx being modified in the utc_to_local call below
	this, and I'm not sure why you would want to add in the fractional
	seconds unless you assumed the timezone conversion would drop the
	existing fractional seconds (TZInfo doesn't drop fractional seconds).
	---
	 test/ruby/test_time_tz.rb | 10 ++++++++++
	 1 file changed, 10 insertions(+)

	Subsecond of Time::tm should be 0

	---
	 time.c | 1 +
	 1 file changed, 1 insertion(+)

1 files changed, 10 insertions, 0 deletions

diff --git a/test/ruby/test_time_tz.rb b/test/ruby/test_time_tz.rb
index 7f0a306783..5ee12e4dbd 100644
--- a/test/ruby/test_time_tz.rb
+++ b/test/ruby/test_time_tz.rb
@@ -749,6 +749,16 @@ class TestTimeTZ::DummyTZ < Test::Unit::TestCase
   def self.make_timezone(tzname, abbr, utc_offset, abbr2 = nil, utc_offset2 = nil)
     TestTimeTZ::TZ.new(tzname, abbr, utc_offset, abbr2, utc_offset2)
   end
+
+  def test_fractional_second
+    x = Object.new
+    def x.local_to_utc(t); t + 8*3600; end
+    def x.utc_to_local(t); t - 8*3600; end
+
+    t1 = Time.new(2020,11,11,12,13,14.124r, '-08:00')
+    t2 = Time.new(2020,11,11,12,13,14.124r, x)
+    assert_equal(t1, t2)
+  end
 end
 
 begin