Add more protection to CleanStage from bad manifests.

Have CleanStage catch most exceptions generated by parsing the
manifest instead of just EnvironmentError.

BUG=chromium-os:23277
TEST=Verified manifest parse error leads to buildroot clobber.

Change-Id: I90679e8a8fae62d8bb9601ad9cc6c9d9e42bdaee
Reviewed-on: https://gerrit.chromium.org/gerrit/31927
Reviewed-by: Brian Harring <ferringb@chromium.org>
Commit-Ready: Ryan Cui <rcui@chromium.org>
Tested-by: Ryan Cui <rcui@chromium.org>
1 file changed