Git.pm: Set GIT_WORK_TREE if we set GIT_DIR

Otherwise git will use the current directory as work tree which will
lead to unexpected results if we operate in sub directory of the
work tree.

Signed-off-by: Frank Lichtenheld <flichtenheld@astaro.com>
Acked-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

perl/Git.pm

@@ -1280,6 +1280,8 @@ sub _cmd_exec {
 	my ($self, @args) = @_;
 	if ($self) {
 		$self->repo_path() and $ENV{'GIT_DIR'} = $self->repo_path();
+		$self->repo_path() and $self->wc_path()
+			and $ENV{'GIT_WORK_TREE'} = $self->wc_path();
 		$self->wc_path() and chdir($self->wc_path());
 		$self->wc_subdir() and chdir($self->wc_subdir());
 	}

t/t9700-perl-git.sh

@@ -29,6 +29,10 @@ test_expect_success \
      git add . &&
      git commit -m "first commit" &&
 
+     echo "new file in subdir 2" > directory2/file2 &&
+     git add . &&
+     git commit -m "commit in directory2" &&
+
      echo "changed file 1" > file1 &&
      git commit -a -m "second commit" &&
 

t/t9700/test.pl

@@ -98,3 +98,16 @@ TODO: {
 	todo_skip 'config after wc_chdir', 1;
 	is($r->config("color.string"), "value", "config after wc_chdir");
 }
+
+# Object generation in sub directory
+chdir("directory2");
+my $r2 = Git->repository();
+is($r2->repo_path, $abs_repo_dir . "/.git", "repo_path (2)");
+is($r2->wc_path, $abs_repo_dir . "/", "wc_path (2)");
+is($r2->wc_subdir, "directory2/", "wc_subdir initial (2)");
+
+# commands in sub directory
+my $last_commit = $r2->command_oneline(qw(rev-parse --verify HEAD));
+like($last_commit, qr/^[0-9a-fA-F]{40}$/, 'rev-parse returned hash');
+my $dir_commit = $r2->command_oneline('log', '-n1', '--pretty=format:%H', '.');
+isnt($last_commit, $dir_commit, 'log . does not show last commit');