Guard cancelFunc with the download mutex and remember a cancellation
that arrives before Execute sets up its context, so the request is
never made. Previously a download cancelled in that window was removed
from the cache but kept running with nobody able to stop it.
Fixespterodactyl/panel#5651
An archive renamed to another extension, such as a .tar.gz renamed to
.zip, was read as a zip inside a gzip stream and failed with "input type
must be an io.ReaderAt and io.Seeker". The format is now taken from the
contents first, and the file name is only used when they are not
recognized.
Fixespterodactyl/panel#5728
dualfroz