Convert the entries in the code path to absolute paths

Rebar will exit with {error,bad_directory} when trying to restore the code
path after it has finished working on a subdirectory if there are invalid
relative paths in it. The problem was seen when executing the last line of
rebar_erlc_compiler:doterl_compile/3 (true = code:set_path(CurrPath)).

src/rebar_core.erl

@@ -76,6 +76,10 @@ process_commands([Command | Rest]) ->
     lists:foreach(fun (D) -> erlang:erase({skip_dir, D}) end, skip_dirs()),
     Operations = erlang:get(operations),
 
+    %% Convert the code path so that all the entries are absolute paths.
+    %% If not, code:set_path() may choke on invalid relative paths when trying
+    %% to restore the code path from inside a subdirectory.
+    true = rebar_utils:expand_code_path(),
     _ = process_dir(rebar_utils:get_cwd(), rebar_config:new(),
                     Command, sets:new()),
     case erlang:get(operations) of

src/rebar_utils.erl

@@ -38,7 +38,8 @@
          abort/2,
          escript_foldl/3,
          find_executable/1,
-         prop_check/3]).
+         prop_check/3,
+         expand_code_path/0]).
 
 -include("rebar.hrl").
 
@@ -156,6 +157,14 @@ find_executable(Name) ->
 prop_check(true, _, _) -> true;
 prop_check(false, Msg, Args) -> ?ABORT(Msg, Args).
 
+%% Convert all the entries in the code path to absolute paths.
+expand_code_path() ->
+    CodePath = lists:foldl(fun (Path, Acc) ->
+                                   [filename:absname(Path) | Acc]
+                           end, [], code:get_path()),
+    code:set_path(lists:reverse(CodePath)).
+
+
 %% ====================================================================
 %% Internal functions
 %% ====================================================================