Issue #16350, part 2: Set unused_data (and unconsumed_tail) correctly in decompressobj().flush().

Additionally, fix a bug where a MemoryError in allocating a bytes object could
leave the decompressor object in an invalid state (with its unconsumed_tail
member being NULL).

Patch by Serhiy Storchaka.
diff --git a/Misc/NEWS b/Misc/NEWS
index 381b1fc..93aec6b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -140,9 +140,11 @@
 Library
 -------
 
-- Issue #16350: zlib.Decompress.decompress() now accumulates data from
+- Issue #16350: zlib.decompressobj().decompress() now accumulates data from
   successive calls after EOF in unused_data, instead of only saving the argument
-  to the last call. Patch by Serhiy Storchaka.
+  to the last call. decompressobj().flush() now correctly sets unused_data and
+  unconsumed_tail. A bug in the handling of MemoryError when setting the
+  unconsumed_tail attribute has also been fixed. Patch by Serhiy Storchaka.
 
 - Issue #12759: sre_parse now raises a proper error when the name of the group
   is missing.  Initial patch by Serhiy Storchaka.