Guess the mimetype of uploaded files when they're unknown.
Review Request #3667 — Created Dec. 14, 2012 and submitted
Guess the mimetype of uploaded files when they're unknown. Browsers can send an empty mimetype when they don't know what kind of file we're working with. This triggers a code path that fails, and even with that fixed, makes a number of files useless. For example, text files without .txt, or images masquerading as .bin files, or shell scripts. Now, if we're not told of a good file type, and `file` exists, we'll use that to determine the type of file. This captures a number of file types we otherwise wouldn't be told about.
Uploaded some files I had sitting around. AUTHORS, some .sh files, renamed PNGs. The thumbnails ended up correct.