blame: select parent commit of merge commit

[thlehmann-ionos]

When navigating the parent commit through the , key, one can navigate to the previous (parent) commit. For merge requests however, this will always navigate to the first parent commit.

In case of Merge commits I'd like to select the parent commit to follow another branch.

For commits with multiple parents the UI could show a menu on top of the selected line with the parent commits including the commit message subject line.