Missing translations are being included as empty strings

[JasonBarnabe]

I use tx pull -a -f (version 1.6.17) to pull in the content for devise-i18n. Transifex project is at https://app.transifex.com/devise-i18n/devise-i18n-1.

Some content has no translation yet. I'm expecting these translation keys to be excluded in the translation files pulled with tx. Instead, they're being included with empty strings. This breaks the library I'm using to handle these translations, as an empty string does not fall back to the English version.

Example: https://app.transifex.com/devise-i18n/devise-i18n-1/translate/#bg/enyml/565570122

Current start of the file:

bg:
  activerecord:
    attributes:
      user:
        confirmation_sent_at: ""
        confirmation_token: ""
        confirmed_at: ""
        created_at: ""
        current_password: Настояща парола

Expected start of the file

bg:
  activerecord:
    attributes:
      user:
        current_password: Настояща парола

Alternate expected start of file:

bg:
  activerecord:
    attributes:
      user:
        confirmation_sent_at:
        confirmation_token:
        confirmed_at:
        created_at:
        current_password: Настояща парола

I have another project that uses this same command, but I don't have the issue there.