Make standard fields more liberal about interpreting empty strings
Summary:
Fixes T3867. We currently show more empty custom field values on task detail pages than we should, for at least two reasons:
- `<select />` fields with an empty string option store `""`, but users reasonably expect this to mean "no value".
- Old fields may have stored empty strings, and migrated forward.
This fix generally aligns behavior with user expectations. We could get more extreme about not storing `""` in the database, but I think this is generally a less surpsing fix.
Test Plan: Made a select with a `"" : "None"` option, selected it, saw it vanish from task detail screen.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T3867
Differential Revision: https://secure.phabricator.com/D7105