prevent another ResourceWarning in GzipFile due to an unclosed myfileobj

Author: graingert

Lib/gzip.py

@@ -250,6 +250,11 @@ def __init__(self, filename=None, mode=None,
                 self._write_gzip_header(compresslevel)
         except BaseException:
             # Avoid a ResourceWarning if the write fails, eg read-only file or KI
+            try:
+                if self.myfileobj is not None:
+                    self.myfileobj.close()
+            finally:
+                self.fileobj = None
             self.fileobj = None
             raise