Open Sublime Merge when blaming at the right line

RMB > Blame line...

Opens Sublime Merge centred on line L. Sublime Merge does `git show` of the file, it doesn't contain current changes (staged or unstaged).

It should take into consideration that I added N or removed -N lines before L, so Sublime Merge should open on line L-N, not N.

Example 1: I press Blame for line 100 in a file where I added 10 lines before that. Blame should open at line 90.

Example 2: I press Blame for line 100 in a file where I added 10 lines before that and removed 20 even before. Blame should open at line 110.