merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/t/Git-SVN/Utils/collapse_dotdot.t

@@ -0,0 +1,23 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use Test::More 'no_plan';
+
+use Git::SVN::Utils;
+my $collapse_dotdot = \&Git::SVN::Utils::_collapse_dotdot;
+
+my %tests = (
+	"foo/bar/baz"			=> "foo/bar/baz",
+	".."				=> "..",
+	"foo/.."			=> "",
+	"/foo/bar/../../baz"		=> "/baz",
+	"deeply/.././deeply/nested"	=> "./deeply/nested",
+);
+
+for my $arg (keys %tests) {
+	my $want = $tests{$arg};
+
+	is $collapse_dotdot->($arg), $want, "_collapse_dotdot('$arg') => $want";
+}