Paperclip::ContentTypeDetector keeps a File object open and thus prevents it from being deleted, moved, etc. until it is closed by the garbage collector.

I was mass-importing images from a zip file and I noticed that I couldn't delete the files after assigning them to Paperclip.

In line 71:

MimeMagic.by_magic(File.open(@filepath)).try(:type)

... the open file is not closed.

Although this problem is unrelated to #1759, #1980 or #1326, it might very well worsen those situations.

IMHO that line should be:

File.open(@filepath) { |f| MimeMagic.by_magic(f).try(:type) }

Shall I make a pull request?