be more strict with empty strings but more relaxed with empty strings.

- Don't match strings that don't start at the beginning of a line, it
  has a legitimate use-case of strings used in subpackages that need to
  be empty
- But match empty strings that declare themselves empty by having "" as
  their value, this was previously ignored because it was how
  subpackages would declare themselves but it would miss lots of
  subpackages