remove .hg-archival.txt in nix-prefetch-hg

Dependencies

• [2] KX5L74EY add nix-prefetch- scripts for now, were externals in svn

Change contents

• edit in src/script/nix-prefetch-hg at line 52
  [2.9662]

  [2.9662]
  + rm -f $tmpArchive/.hg_archival.txt