The attached file produces the following stacktrace when opened via `tarfile.open`, on Python 3.7.5rc1:


```
$ cat tarrepro.py 
import tarfile
import sys

with tarfile.open(sys.argv[1], errorlevel=2) as t:
  for member in t.getmembers():
    pass
$
```

```
$ python3 tarrepro.py crash-f4032ed3c7c2ae59a8f4424e0e73ce8b11ad3ef90155b008968f5b1b08499bc4
Traceback (most recent call last):
  File "tarrepro.py", line 4, in <module>
    with tarfile.open(sys.argv[1], errorlevel=2) as t:
  File "/usr/lib/python3.7/tarfile.py", line 1574, in open
    return func(name, "r", fileobj, **kwargs)
  File "/usr/lib/python3.7/tarfile.py", line 1646, in gzopen
    t = cls.taropen(name, mode, fileobj, **kwargs)
  File "/usr/lib/python3.7/tarfile.py", line 1622, in taropen
    return cls(name, mode, fileobj, **kwargs)
  File "/usr/lib/python3.7/tarfile.py", line 1485, in __init__
    self.firstmember = self.next()
  File "/usr/lib/python3.7/tarfile.py", line 2290, in next
    tarinfo = self.tarinfo.fromtarfile(self)
  File "/usr/lib/python3.7/tarfile.py", line 1094, in fromtarfile
    buf = tarfile.fileobj.read(BLOCKSIZE)
  File "/usr/lib/python3.7/gzip.py", line 276, in read
    return self._buffer.read(size)
  File "/usr/lib/python3.7/_compression.py", line 68, in readinto
    data = self.read(len(byte_view))
  File "/usr/lib/python3.7/gzip.py", line 463, in read
    if not self._read_gzip_header():
  File "/usr/lib/python3.7/gzip.py", line 421, in _read_gzip_header
    self._read_exact(extra_len)
  File "/usr/lib/python3.7/gzip.py", line 400, in _read_exact
    raise EOFError("Compressed file ended before the "
EOFError: Compressed file ended before the end-of-stream marker was reached

```