find_content_type(), can_compress_content_type() and
is_prohibited_header_name() switched on a 26-bit hash of the name and
never compared the name itself, so any name that hashed alike was taken
for a known one. An uploaded file with an unknown extension could be
served as text/html, for one.
Compare the names themselves, and drop the hash and its literal
operator, which nothing else uses.
yhirose
6acdc6255d
