Had a surprising result of an import tree merge. I am importing photos
from my phone. I had earlier imported some photos and moved the whole tree
containing them from  phone/DCIM to raw/photos/something. Then I took a new photo,
and imported again.

one. In commit cd55a5be377020b7261c3a737b5e32a01e22f4b8 "import from phone"
that added a `phone/DCIM/Camera/IMG_20190516_111640.jpg`.

But then in the merge commit a548a51de2566c26f74b5791eb0660e4d79e2cb7
that merged phone/master into master, the new photo moved into
raw/photos/something

This is quite surprising. It seems somehow when it modified the old
tree, it rooted the new at the location the old had been moved to in
master.