Re: gitk "find commit adding/removing string"/possible pickaxe bug?

Thomas Rast [off-list ref] writes:

  git log -Squux --pickaxe-all -c -p  # shows merge & combined diff

So it only shows the diff with --pickaxe-all, even though the (only)
hunk clearly introduced the string.

Isn't it just because unless you ask for -m to get all the pairwise diff
between each parent and the merged child the diff machinery won't kick in
for merge commits?  I didn't check the option defaulting logic, but there
may be something that changes the default setting of "-m" among your
examples.