Change image extension when converting formats.

[nashby]

It's a new version of #404 but I think it should be default behaviour and we don't need that rename option. @bensie what do you think?

[bensie]

Looks great!

[mterenzio]

Was this reverted at some point? It wasn't working for me and I notice the relevant code is no longer in Master

[dem1tris]

@mterenzio Same question. It must be delegated to imageprocessing gem, but now it doesn't work

[mshibuya]

@mterenzio @dem1tris Then could you open a new issue? Thanks.

[dem1tris]

@mshibuya It seems like #2125, #2126, #2127 are still actual.
As I debugged yesterday, cause is probably in CarrierWave::Storage::File#cache!.
Here is new_file.move_tonew_file.move_to(::File.expand_path(uploader.cache_path, uploader.root), uploader.permissions, uploader.directory_permissions, true) with the keep_filename == true.

Now new_path is formed from uploader's point of view which creates "foo/bar/version_origname.origext". But new_file at this moment is already named properly by imageprocessing: "/some/path/origname.newext". Although keep_filename == true passes original_filename as filename in hash, file path is rewritten now and ending with old extension again.

Btw, I found the hint in Readme section about RMagick:

def filename
      super.chomp(File.extname(super)) + '.newext' if original_filename.present?
end

Putting it inside version helped me. But it shouldn't be necessary with MiniMagick.

UPD. Replaced with

def full_filename(for_file)
      for_file.chomp(File.extname(for_file)) + '.newext'
end