Delete `--is_stderr_atty`
We're well past the date we said we should delete it after.
@@ -173,9 +173,6 @@ public class UiOptions extends OptionsBase {
@Option(
name = "isatty",
- // TODO(b/137881511): Old name should be removed after 2020-01-01, or whenever is
- // reasonable.
- oldName = "is_stderr_atty",
defaultValue = "false",
metadataTags = {OptionMetadataTag.HIDDEN},
documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
