bunpen: fix last failing integration test

pkgs/additional/bunpen/default.nix

@@ -12,7 +12,7 @@
 
   nativeCheckInputs = [ which ];
 
-  # doCheck = true;  #< TODO: fix tests!
+  doCheck = true;
 
   meta = {
     description = "userspace sandbox helper";

pkgs/additional/bunpen/main.ha

@@ -19,7 +19,7 @@ fn do_exec(path: str, args: []str) (os::exec::error | void) = {
     log::printfln("exec {} with argv: {}", path, joined);
   };
 
-  errors::ext::check("exec", rt::ext::execve(path, args, os::getenvs()));
+  errors::ext::check("exec", rt::ext::execvpe(path, args, os::getenvs()));
 
   // XXX: os::exec::exec offers no way to preserve argv0, but it does
   // work if you don't care about that: