I have just noticed that talked about "previous" ("parent") header was added to --porcelain/--incremental output of git-blame in 96e1170 (blame: show "previous" information in --porcelain/--incremental format).
It didn't get documented however. My question is if <sha1> in "previous <sha1> <filename>" is <sha1> of parent (taking grafts and refs/replace into account), or is it <sha1> of _effective_ parent for given line?
-- Jakub Narebski Poland