Fix lib.chroot_lib_unittest.

This switches to using cros_build_lib_unittest.RunCommandTempDirTestCase
instead of mocking RunCommand directly.

BUG=brillo:866
TEST=Unit tests pass.

Change-Id: I327b45f68129286f9cbb770d1641c1e439e5137e
Reviewed-on: https://chromium-review.googlesource.com/267740
Trybot-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed