Some post-review changes:

- restore path after loading applications,
- helpful comments.

src/rebar_prv_common_test.erl

@@ -221,9 +221,13 @@ select_tests(State, ProjectApps, CmdOpts, CfgOpts) ->
     Configs = lists:flatmap(fun(Filename) ->
                                 rebar_file_utils:consult_config(State, Filename)
                             end, SysConfigs),
+    %% NB: load the applications (from user directories too) to support OTP < 17
+    %% to our best ability.
+    OldPath = code:get_path(),
     code:add_pathsa(rebar_state:code_paths(State, all_deps)),
     [application:load(Application) || Config <- Configs, {Application, _} <- Config],
     rebar_utils:reread_config(Configs),
+    code:set_path(OldPath),
 
     Merged = lists:ukeymerge(1,
                              lists:ukeysort(1, CmdOpts),

src/rebar_utils.erl

@@ -414,6 +414,8 @@ user_agent() ->
     ?FMT("Rebar/~s (OTP/~s)", [Vsn, otp_release()]).
 
 reread_config(ConfigList) ->
+    %% NB: we attempt to mimic -config here, which survives app reload,
+    %% hence {persistent, true}.
     SetEnv = case version_tuple(?MODULE:otp_release()) of
         {X, _, _} when X =< 17 ->
             fun application:set_env/3;