dummy_thread.acquire() would return None if no waitflag argument was given. It
should have returned True.

Fixes issue #3339. Thanks, Henk Punt for the report and Andrii v. Mishkovskiyi
for attempting a patch.
diff --git a/Misc/NEWS b/Misc/NEWS
index f026a09..ecd5567 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,7 +10,6 @@
 Core and Builtins
 -----------------
 
-
 - Issue #2517: Allow unicode messages in Exceptions again by correctly
   bypassing the instance dictionary when looking up __unicode__ on
   new-style classes.
@@ -41,6 +40,8 @@
 Library
 -------
 
+- Issue #3339: dummy_thread.acquire() should not return None.
+
 - Issue #3285: Fractions from_float() and from_decimal() accept Integral arguments.
 
 - Issue #3301: Bisect module behaved badly when lo was negative.