The only change I see to sudo between 5.3 and 5.4 that might be
related is this one. You could try backing it out via "patch -R"
and see if the old behavior is restored.
- todd
Index: sudo.c
===================================================================
RCS file: /home/cvs/openbsd/src/usr.bin/sudo/sudo.c,v
retrieving revision 1.43
diff -u -r1.43 sudo.c
--- sudo.c 8 Jul 2010 21:11:31 -0000 1.43
+++ sudo.c 6 Nov 2013 20:14:47 -0000
@@ -305,7 +305,7 @@
log_error(NO_STDERR|NO_EXIT, "problem with defaults entries");
/* Set login class if applicable. */
- set_loginclass(sudo_user.pw);
+ set_loginclass(runas_pw ? runas_pw : sudo_user.pw);
/* Update initial shell now that runas is set. */
if (ISSET(sudo_mode, MODE_LOGIN_SHELL))
