git-svn: keep timestamp of git commit date when do "git svn dcommit"

git-svn.perl.diff

--- git-svn.perl.orig	2017-07-09 03:29:19.208317700 +0900
+++ git-svn.perl	2017-07-11 23:17:29.997533800 +0900
@@ -16,6 +16,7 @@
 use File::Spec;
 use Getopt::Long qw/:config gnu_getopt no_ignore_case auto_abbrev/;
 use Memoize;
+use POSIX qw/strftime/;
 
 use Git::SVN;
 use Git::SVN::Editor;
@@ -52,6 +53,8 @@
 	Memoize::memoize 'Git::config_bool';
 }
 
+# avoid to output "Wide character in print at"
+binmode(STDOUT, ":utf8");
 
 # From which subdir have we been invoked?
 my $cmd_dir_prefix = eval {
@@ -995,9 +998,12 @@
 				                             $rewritten_parent);
 			}
 
+			my $ra = Git::SVN::Ra->new($url);
+			my $log_entry = get_commit_entry($d);
+
 			my %ed_opts = ( r => $last_rev,
-			                log => get_commit_entry($d)->{log},
-			                ra => Git::SVN::Ra->new($url),
+			                log => $log_entry->{log},
+			                ra => $ra,
 			                config => SVN::Core::config_get_config(
 			                        $Git::SVN::Ra::config_dir
 			                ),
@@ -1023,9 +1029,13 @@
 				$gs->{inject_parents_dcommit}->{$cmt_rev} =
 				                               $parents->{$d};
 			}
+
+			my $author_date = strftime("%Y-%m-%dT%H:%M:%S.000000Z", gmtime($log_entry->{date}));
+			$ra->change_rev_prop($cmt_rev, 'svn:date', $author_date);
 			$_fetch_all ? $gs->fetch_all : $gs->fetch;
 			$SVN::Error::handler = $err_handler;
 			$last_rev = $cmt_rev;
+
 			next if $_no_rebase;
 
 			my @diff = dcommit_rebase(@$linear_refs == 0, $d,
@@ -1852,7 +1862,11 @@
 		while (<$msg_fh>) {
 			if (!$in_msg) {
 				$in_msg = 1 if (/^$/);
-				$author = $1 if (/^author (.*>)/);
+				if (/^author (.*>) (\d+) ([\-\+]?\d+)$/o) {
+					$author = $1;
+					my($t, $tz) = ($2, $3);
+					$log_entry{date} = Git::SVN::Log::parse_git_date($t, $tz);
+				}
 			} elsif (/^git-svn-id: /) {
 				# skip this for now, we regenerate the
 				# correct one on re-fetch anyways

How to use this script. Any instructions on usage would be helpful.