Please consider making the `*E` backends lower-case the file extensions. This improves deduplication especially with image files, where cameras often use `*.JPG`, while other software such as the Dropbox Android app rename the images to `*.jpg`.
We talked about that very shortly a few months ago:

(Log starts 2015-08-06 21:11:40 CET)

     tribut  is there a backend that lowercases the extension? or do the *E backends do that anyway?
     joeyh   it does not
     tribut  but would it make sense? or am i missing something?
     joeyh   I don't know.. the extension is only there for stupid programs that follow symlinks and
             check extensions. If such a program cares about .GIF vss .gif, you might have a problem
     joeyh   I think that you can git-annex migrate from hashE to hash, then migrate back, and it'll
             update to the new file extension.
     tribut  i was thinking about content-identical images with .JPG or .jpg extension
     tribut  and because even the most retarded of programs wont care, i thought the backend could
             lowercase the extension
     joeyh   ah, sure, using the E backend reduces the ability to de-duplicate
     joeyh   I'd not want to add a e backend set just for this. There's no requirement that the
             extension extraction code be stable, so it could be considered changing it to lower-case
     joeyh   otoh, I have no idea if some programs are dumb enough to care about .git vs .GIF
