Show other revisions of a file with magit

Magit proper offers magit-find-file and magit-find-file-other-window, that ask you for both revision and file. At least they autocomplete with sane defaults. 

The thing is my usecase is 99% "current-file in previous-branch in a split window".

As easy as

(defun rgc/magit-find-file-dwim ()
  (interactive)
  (magit-find-file-other-window (magit-get-previous-branch) (buffer-file-name)))

You get a nice command to open the current file from the previous branch you visited in your repo. 

Often, next immediate  command is m-x ediff-buffers RET. (yeah, maybe adding that would make it even more dwim).

If you'd want to do it in the command line, something like 

    git show branch:file

Would do, but you'd have to type both branch and filename.