backport from the trunk, to fix test_tools with srcdir != builddir

changeset:   77827:c23b442b5d5e
	user:        Antoine Pitrou <solipsis@pitrou.net>
	date:        Thu Jun 28 01:20:26 2012 +0200
	summary:     Avoid using scrdir, it's broken.

	changeset:   77826:f0e58e778215
	user:        Neil Schemenauer <nas@arctrix.com>
	date:        Wed Jun 27 15:58:37 2012 -0600
	summary:     Fix bug in test_tools that prevented building is separate directory.