Fix reading files from servers without support for range requests
Fix reading files from servers without support for range requests

Example traceback with debugging print out without this fix applied:

Got response of size 20166303 chunksize is 1048576
-1765915941 -30694 -1671616656 4090602292 -7813 16221 -118717542 708660270
self._compressedbytes, self._uncompressedbytes = -1765908128 -1671616656
cursor.index - start 0
self._compressedbytes -1765908128
self._uncompressed = None
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "uproot/rootio.py", line 60, in open
    return http(path, httpsource=httpsource, **options)
  File "uproot/rootio.py", line 89, in http
    return ROOTDirectory.read(openfcn(path), **options)
  File "uproot/rootio.py", line 154, in read
    streamerinfos, streamerinfosmap, streamerrules = _readstreamers(streamerkey._source, streamerkey._cursor, streamercontext, None)
  File "uproot/rootio.py", line 556, in _readstreamers
    tlist = TList.read(source, cursor, context, parent)
  File "uproot/rootio.py", line 949, in read
    out = cls._readinto(out, source, cursor, context, parent)
  File "uproot/rootio.py", line 1455, in _readinto
    start, cnt, self._classversion = _startcheck(source, cursor)
  File "uproot/rootio.py", line 426, in _startcheck
    cnt, vers = cursor.fields(source, _startcheck._format_cntvers)
  File "uproot/source/cursor.py", line 46, in fields
    return format.unpack(source.data(start, stop))
  File "uproot/source/compressed.py", line 183, in data
    return self._uncompressed[start:stop]
TypeError: 'NoneType' object is not subscriptable

scikit-hep/uproot,scikit-hep/uproot,scikit-hep/uproot,scikit-hep/uproot