Sends a HEAD request, falling back to simulation when the server does not support HEAD. Tries, in order:
HEAD
fetch()
Range
GET
Sends a
HEADrequest, falling back to simulation when the server does not supportHEAD. Tries, in order:HEADrequest viafetch().RangeGET to retrieve the first FILE_TYPE_MAGIC_NUMBER_SIZE bytes (magic-number file header).GETthat reads the first FILE_TYPE_MAGIC_NUMBER_SIZE bytes then cancels the body stream.