gnu-tar: install as gtar, link gnubin/tar -> gtar

dpkg needs gnu-tar to install with a well-known name, so we mimic the
setup used by coreutils of always installing with the 'g' prefix, and
offering the clashing executable name in $opt/libexec/gnubin.

Signed-Off-By: Drew Fisher <zarvox@zarvox.org>

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/gnu-tar.rb

@@ -6,13 +6,24 @@ class GnuTar < Formula
   mirror 'http://ftp.gnu.org/gnu/tar/tar-1.26.tar.gz'
   sha1 'ba89cba98c1a6aea3c80cda5ddcd5eceb5adbb9b'
 
-  option 'default-names', "Do not prepend 'g' to the binary"
-
   def install
     args = ["--prefix=#{prefix}", "--mandir=#{man}"]
-    args << "--program-prefix=g" unless build.include? 'default-names'
+    args << "--program-prefix=g"
 
     system "./configure", *args
     system "make install"
+
+    # Symlink the executable into libexec/gnubin as "tar"
+    (libexec/'gnubin').install_symlink bin/"gtar" => "tar"
+  end
+
+  def caveats; <<-EOS.undent
+    gnu-tar has been installed as 'gtar'.
+
+    If you really need to use it as 'tar', you can add a 'gnubin' directory
+    to your PATH from your bashrc like:
+
+        PATH="#{opt_prefix}/libexec/gnubin:$PATH"
+    EOS
   end
 end