add an option to soft purge rather than purge old code

at the cost of some SASL warnings this prevents rebar3 from terminating
processes when reloading their code before running tests

src/rebar_prv_common_test.erl

@@ -38,7 +38,7 @@ init(State) ->
 -spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     ?INFO("Running Common Test suites...", []),
-    rebar_utils:update_code(rebar_state:code_paths(State, all_deps)),
+    rebar_utils:update_code(rebar_state:code_paths(State, all_deps), [soft_purge]),
 
     %% Run ct provider prehooks
     Providers = rebar_state:providers(State),

src/rebar_prv_eunit.erl

@@ -49,7 +49,7 @@ do(State) ->
 do(State, Tests) ->
     ?INFO("Performing EUnit tests...", []),
 
-    rebar_utils:update_code(rebar_state:code_paths(State, all_deps)),
+    rebar_utils:update_code(rebar_state:code_paths(State, all_deps), [soft_purge]),
 
     %% Run eunit provider prehooks
     Providers = rebar_state:providers(State),

src/rebar_utils.erl

@@ -47,6 +47,7 @@
          deprecated/4,
          indent/1,
          update_code/1,
+         update_code/2,
          remove_from_code_path/1,
          cleanup_code_path/1,
          args_to_tasks/1,
@@ -644,7 +645,9 @@ indent(Amount) when erlang:is_integer(Amount) ->
 
 %% Replace code paths with new paths for existing apps and
 %% purge code of the old modules from those apps.
-update_code(Paths) ->
+update_code(Paths) -> update_code(Paths, []).
+
+update_code(Paths, Opts) ->
     lists:foreach(fun(Path) ->
                           Name = filename:basename(Path, "/ebin"),
                           App = list_to_atom(Name),
@@ -654,19 +657,18 @@ update_code(Paths) ->
                                   code:add_patha(Path),
                                   ok;
                               {ok, Modules} ->
-                                  %% stick rebar ebin dir before purging to prevent
-                                  %% inadvertent termination
-                                  RebarBin = code:lib_dir(rebar, ebin),
-                                  ok = code:stick_dir(RebarBin),
                                   %% replace_path causes problems when running
                                   %% tests in projects like erlware_commons that rebar3
                                   %% also includes
                                   %code:replace_path(App, Path),
                                   code:del_path(App),
                                   code:add_patha(Path),
-                                  [begin code:purge(M), code:delete(M) end || M <- Modules],
-                                  %% unstick rebar dir
-                                  ok = code:unstick_dir(RebarBin)
+                                  case lists:member(soft_purge, Opts) of
+                                      true  ->
+                                          [begin code:soft_purge(M), code:delete(M) end || M <- Modules];
+                                      false ->
+                                          [begin code:purge(M), code:delete(M) end || M <- Modules]
+                                  end
                           end
                   end, Paths).