Update the news.

Author: dak180

NEWS

@@ -4,6 +4,8 @@ Repository head:
   Make sure we do not get a tag where we need a branch.
   Do not emit warnings about nonexistent tags.
   Add option -C for changing working directory.
+  Add a subcommand check.
+  Replace if chains with case.
 
 1.21 @ 2017-09-30:
   Try to make tarballs more reproducible.