@witty-crayon-22786 btw, the error message from returning an

Err

in

expand()

is great -- i obviously need to fix the message but plenty of context i think

Exception message: Build graph construction failed: ExecutionError Received unexpected Throw state(s):
Computing Select(Specs(dependencies=(DescendantAddresses(directory=u''),)), =TransitiveHydratedTargets)
  Computing Task(transitive_hydrated_targets, Specs(dependencies=(DescendantAddresses(directory=u''),)), =TransitiveHydratedTargets)
    Computing Task(transitive_hydrated_target, tests/python/pants_test/backend/jvm/tasks/coverage:coverage, =TransitiveHydratedTarget)
      Computing Task(hydrate_target, tests/python/pants_test/backend/jvm/tasks/coverage:coverage, =HydratedTarget)
        Computing Task(hydrate_sources, SourcesField(address=BuildFileAddress(tests/python/pants_test/backend/jvm/tasks/coverage/BUILD, coverage), arg=sources, filespecs={u'exclude': [], u'globs': [u'test_*.py', u'*_test.py']}), =HydratedField)
          Computing Snapshot(Key { id: 3324, type_id: TypeId(94630918927376) })
            Throw(PathGlobs expansion failed: Throw(???/globs with exclude patterns Gitignore { set: GlobSet { len: 0, strats: [] }, root: "", globs: [], num_ignores: 0, num_whitelists: 0, matches: ThreadLocal { local_data: None } } did not match: ["\"tests/python/pants_test/backend/jvm/tasks/coverage/*_test.py\""], "<pants native internals>"))
              Traceback (no traceback):
                <pants native internals>
              Exception: PathGlobs expansion failed: Throw(???/globs with exclude patterns Gitignore { set: GlobSet { len: 0, strats: [] }, root: "", globs: [], num_ignores: 0, num_whitelists: 0, matches: ThreadLocal { local_data: None } } did not match: ["\"tests/python/pants_test/backend/jvm/tasks/coverage/*_test.py\""], "<pants native internals>")