git-gui: Better positioning in Blame Parent Commit
git-gui: Better positioning in Blame Parent Commit

Invoke diff-tree between the commit and its parent,
and use the hunks to fix the target line number,
accounting for addition and removal of lines.

Signed-off-by: Alexander Gavrilov <75c96f70141fec65a655d202cd4821a09cb99fd1@gmail.com>
Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git