Replace the shell.

It allows to directly control firefox from supervisord if needed.

component/firefox/buildout.cfg

@@ -36,7 +36,7 @@ script =
   cd %(location)s
   export LD_LIBRARY_PATH=%(location)s:${libXrender:location}/lib/:${freetype:location}/lib/:${fontconfig:location}/lib/:${libX11:location}/lib/:${bzip2:location}/lib/:${libXext:location}/lib/:${libXt:location}/lib/:${zlib:location}/lib/:${libXcursor:location}/lib/:${gtk-2:location}/lib/:${cairo:location}/lib/:${pango:location}/lib/:${glib:location}/lib/:${atk:location}/lib/:${gdk-pixbuf:location}/lib/:${alsa:location}/lib/:${libpng:location}/lib/:${libSM:location}/lib/:${libICE:location}/lib:${libxml2:location}/lib:${openssl:location}/lib
   export PATH=${fontconfig:location}/bin:$PATH
-  %(location)s/firefox $*""")
+  exec %(location)s/firefox $*""")
   wrapper.close()
   os.chmod(wrapper_location, 0777)