gnulib-tool.py: Follow gnulib-tool changes, part 62. Follow gnulib-tool change 2020-02-22 Bruno Haible <bruno@clisp.org> gnulib-tool: Ensure copied files are writable. * pygnulib/constants.py (ensure_writable): New function. Make sure files are writable. (symlink_relative, hardlink): Use it. * pygnulib/GLFileSystem.py (GLFileSystem.lookup) (GLFileAssistant.add_or_update): Likewise. * pygnulib/GLTestDir.py (GLTestDir.execute): Likewise. * pygnulib/main.py (main): Likewise.