Adding simple checks for necessary version of ERTS + Reltool

src/rebar.erl

@@ -27,6 +27,26 @@
 -export([main/1]).
 
 main(Args) ->
+    %% HACK: Make sure the caller is running w/ r13b03 and reltool >= 0.5.2
+    case erlang:system_info(version) < "5.7.4" of
+        true ->
+            io:format("Rebar requires at least erts 5.7.4; this VM is using ~s\n",
+                      [erlang:system_info(version)]),
+            halt(1);
+        false ->
+            ok
+    end,
+
+    ReltoolVsn = filename:basename(code:lib_dir(reltool)),
+    case ReltoolVsn < "reltool-0.5.2" of
+        true ->
+            io:format("Rebar requires at least reltool-0.5.2; this VM is using ~s\n",
+                      [ReltoolVsn]),
+            halt(1);
+        false ->
+            ok
+    end,
+    
     case catch(rebar_core:run(Args)) of
         ok ->
             ok;