How to get proper diff of merge commit in tig -

if got tig main view, nice graph of commits , merges. i'd prefer @ merge commits trunk unlike normal commits tig tig shows full diff file contents, on merge commits shows list of changed files in diff view. how tig display file contents diff on merge commits?

commit fb56223ec50cf659a308b3c9979c912881147689
refs: [master], {origin/master}, {origin/head}, juju-1.21-alpha1-229-gfb56223
merge: 7e7c95d a017b5a
author: juju bot
authordate: mon sep 22 01:22:03 2014 +0100
commit: juju bot
commitdate: mon sep 22 01:22:03 2014 +0100

merge pull request #803 mjs/check-ssh-api-methods-are-allowed-during-upgrade  cmd/juju: ensure api calls used "juju ssh" allowed during upgrades  had regression api call required "juju ssh" wasn't being allowed api server while upgrades in progress. "juju ssh" 1 of few commands supposed work during upgrades.                                                    client used "juju ssh" forced interface , checked using reflection against api server allow during upgrades. effectively, compiler helps check required api methods allowed.  http://reviews.vapour.ws/r/64/diff/                                                                                                                                                                                                                                            

apiserver/upgrading_root.go | 20 +++++++++++---------
cmd/juju/ssh.go | 15 +++++++++++----
cmd/juju/ssh_test.go | 24 ++++++++++++++++++++++++
3 files changed, 46 insertions(+), 13 deletions(-)

navigating individual files (j/k) in view, says press 'enter' view file diff, hitting enter gets "failed find file diff" err message. ideally i'd looking @ combined diff merge commit.

[update] traced through tig sysdig , looks doing following on merge commits won't show actual diff. git show --encoding=utf-8 --pretty=fuller --root --patch-with-stat --show-notes --no-color fb56223ec50cf659a308b3c9979c912881147689 --

i guess i'm looking on merge commits parse parents commits , following git diff 7e7c95d a017b5a

[update] diff isn't correct here diff between 2 parents, , more inclusive of changes merge itself, best content rendering of diff seems be

git diff fb56223^ fb56223

turns out pretty straightforward via external command integration, dropped ~/.tigrc , press 7 diff output i'm looking.

bind diff 7 !git diff %(commit)^ %(commit)