[vim] - wincmd L doesn't work in :Bro on previously existing files

[duketuxem]

Normal behavior:

When calling The Bro function (declared in vimrc) with <leader> r for example, selecting an existing (non-empty) old file path will display it on a new vim right pane.

Issue:
Now, doing the same for a previously existing file, does open a new buffer (displayed [new] in the console), but somehow the wincmd does not seem to be executed. Once the function exits, if the user types:
:wincmd L this results in the desired behavior, why is this not working from the function scope ?