- :yield: tuples of (field, value), one per header line, in the order read
- from the text, possibly including duplicates. Includes a field named
- None for the freeform tag/commit text.
+ :return: iterator of tuples of (field, value), one per header line, in the
+ order read from the text, possibly including duplicates. Includes a
+ field named None for the freeform tag/commit text.