uploadComplete() leaves _is_firmware / _is_filesystem set after a
successful upload. When the client then closes the connection,
handleDisconnect() sees the flags, treats it as an aborted upload and
sets the status back to NORMAL, cancelling the pending restart. The WebUI
gets away with it because its status poll turns the pending restart into
a requested one first; an upload from curl or a script is accepted
(md5_ok) but the device keeps running the old firmware until something
else restarts it.
Clear the flags once the upload has completed.
Chris Sutcliff