or some form of "git clean -x". It's probably simpler and safer to
make a new working directory exclusively for the release branch.
+ If the working directory has subdirectories created when making
+ previous releases or pretests, remove those subdirectories, as the
+ command which updates the ChangeLog file might attempt to recurse
+ there and scan any ChangeLog.* files there.
+
Make sure the tree is built, or at least configured. That's
because some of the commands below run Make, so they need
Makefiles to be present.