Merge pull request #1650 from ferd/prevent-crash-on-dup-plugin-paths

Prevent hard crash on duplicate plugin paths

src/rebar_core.erl

@@ -136,6 +136,7 @@ process_command(State, Command) ->
 do([], State) ->
     {ok, State};
 do([ProviderName | Rest], State) ->
+    ?DEBUG("Provider: ~p", [ProviderName]),
     %% Special providers like 'as', 'do' or some hooks may be passed
     %% as a tuple {Namespace, Name}, otherwise not. Handle them
     %% on a per-need basis.

src/rebar_utils.erl

@@ -766,7 +766,7 @@ remove_from_code_path(Paths) ->
                                   [begin code:purge(M), code:delete(M) end || M <- Modules]
                           end,
                           code:del_path(Path)
-                  end, Paths).
+                  end, lists:usort(Paths)).
 
 %% @doc Revert to only having the beams necessary for running rebar3 and
 %% plugins in the path