packaging: Add the project directory to sys.path to support local setup hooks.

Original patch by Vinay Sajip on #11637.
diff --git a/Misc/NEWS b/Misc/NEWS
index c05a32a..89eab0e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -193,7 +193,10 @@
 Library
 -------
 
-- Issue #6771: moved the curses.wrapper function from the single-function
+- Issue #11637: Fix support for importing packaging setup hooks from the
+  project directory.
+
+- Issue #6771: Moved the curses.wrapper function from the single-function
   wrapper module into __init__, eliminating the module.  Since __init__ was
   already importing the function to curses.wrapper, there is no API change.