gnulib-tool --lgpl doesn't convert gplv3 to lgplv2.1

[Simon Josefsson]

I noticed this for the dummy.c module, which after been imported with
--lgpl said:

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

The dummy.c in gnulib contains the GPLv3 header, and the modules file
says LGPLv2+.

The patch below fixes this, but I'm not sure if there are other
unintended consequences.  Comments?  Ok to install?

Thanks,
Simon

diff --git a/gnulib-tool b/gnulib-tool
index 1003f4c..b35d736 100755
--- a/gnulib-tool
+++ b/gnulib-tool
@@ -2237,7 +2237,7 @@ func_import ()
       # Update license.
       sed_transform_lib_file=$sed_transform_lib_file'
         s/GNU General/GNU Lesser General/g
-        s/version 2\([ ,]\)/version 2.1\1/g
+        s/version [23]\([ ,]\)/version 2.1\1/g
       '
     fi
   fi