anchor.diff:  %%% Remove prefix and make path relative
   %%%
   -spec rm_prefix(uri(), string()) -> uri().
  -rm_prefix(#uri{path=Path}=Uri, Prefix) ->
  +rm_prefix(#uri{path=Path}=Uri, Prefix) -> 
  +    lager:debug("### rm_prefix(~p, ~p)~n", [Path, Prefix]),
       case substr(Prefix, Path) of
   	{ok, Path2} -> #uri{path=Path2};
   	none -> Uri
  
positive.code:     none;
  substr([C|S1], [C|S2], _MakeRel) ->
      substr(S1, S2, true);
  substr([], S2, true) ->
      {ok, filename:join(S2)};
  substr(_S1, _S2, false) ->
  
negative.code: 		  #uri{scheme=http, host="example.com", port=99, path="/what/a/prefix/path/to/a/resource"}),
       ?_assert(rm_prefix(Uri, "/what/a/prefix") =:= 
  		  #uri{scheme=http, host="example.com", port=99, path="/what/a/prefix/path/to/a/resource"}),
       ?_assert(rm_prefix(Uri, "/") =:= #uri{path="what/a/prefix/path/to/a/resource"}),
       ?_assert(rm_prefix(Uri2, "/a/long/prefix") =:= #uri{path="/resource"}),
       ?_assert(rm_prefix(Uri2, "/resource/") =:= #uri{path="/resource"})
      ].
      
  -endif.
  