build_image: workaround eselect python bug with no man pages

The eselect tool has a bug where eselect python fails when there are
no man pages.  Add a small workaround for it.

BUG=b:187794810
TEST=CQ passes

Change-Id: Ib6301bfaf1451ed65c1b36dc020887b5807fbd76
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3621321
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Sloan Johnson <sloanjohnson@google.com>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed