As found by Mikhail, gotd regress test script run as root when the
test suite is invoked via doas(1). This happens because doas sets
the $LOGNAME environment veriable to the target user (root). Unlike
su(1) which leaves $LOGNAME set to the name of the original user.

This patch adds a sanity check to prevent running test scripts as root,
and switches to $USERNAME which works with both doas(1) and su(1).

This does not fix 'su -', which leaves $USERNAME unset and also sets
$LOGNAME to root. That is no big deal; people can just avoid 'su -',
or pass their intended GOTD_TEST_USER on the make command line.

ok?

 make it easier to run gotd regress via doas(1)
 
diff b1142068fd26fa24285c533f10e3afcb61719759 32014c96a26e67fa0bf2fc74139ec6b68336c966
commit - b1142068fd26fa24285c533f10e3afcb61719759
commit + 32014c96a26e67fa0bf2fc74139ec6b68336c966
blob - cd20ee9bf8631fcd757767edf78df5f410e56161
blob + 1f10771a98fe00cf4c3029d94a41ae32341873e7
--- regress/gotd/Makefile
+++ regress/gotd/Makefile
@@ -12,7 +12,7 @@ GOTD_TEST_USER?=${LOGNAME}
 GOTD_TEST_REPO!?=mktemp -d "$(GOTD_TEST_ROOT)/gotd-test-repo-XXXXXXXXX"
 GOTD_TEST_REPO_URL=ssh://${GOTD_DEVUSER}@127.0.0.1/test-repo
 
-GOTD_TEST_USER?=${LOGNAME}
+GOTD_TEST_USER?=${USERNAME}
 GOTD_TEST_USER_HOME!=userinfo $(GOTD_TEST_USER) | awk '/^dir/ {print $$2}'
 
 # gotd.conf parameters
@@ -34,8 +34,12 @@ ensure_root:
 
 ensure_root:
 	@if [[ `id -u` -ne 0 ]]; then \
-		echo gotd test suite must be run by root >&2; \
+		echo gotd test suite must be started by root >&2; \
 		false; \
+	fi ; \
+	if [[ "$(GOTD_TEST_USER)" = "root" ]]; then \
+		echo GOTD_TEST_USER must be a non-root user >&2; \
+		false; \
 	fi
 
 start_gotd_ro: ensure_root