fix(provtest,dhcptest): refuse a second setup over a live fixture

Both fixtures record what they are about to change so teardown can put
it back, and both truncated that record on entry. A setup run while one
was already up therefore saved the fixture's own site table, dhcpd.conf
and /etc/hosts as the originals, and the veth and namespace it no longer
knew about survived the teardown that followed.

Refuse when the state directory is there, naming the teardown to run.

xCAT-test/autotest/testcase/dhcptest/dhcpfixture.sh

@@ -301,6 +301,10 @@ do_check() {
 }
 
 do_setup() {
+    # A second setup over a live fixture would save the fixture's own dhcpd.conf
+    # and site table as the originals, so teardown would restore them instead of
+    # what was there first. Refuse rather than leave the machine in that state.
+    [ -d "$STATE" ] && die "a fixture is already up; run '$0 teardown' first"
     mkdir -p "$STATE" || die "cannot create $STATE"
 
     # Recorded before it is changed, so teardown is exact rather than a guess.

xCAT-test/autotest/testcase/provtest/provfixture.sh

@@ -463,6 +463,11 @@ define_node() {
 
 do_setup() {
     local tmpl http dns tftp
+    # A second setup over a live fixture would overwrite the record teardown
+    # restores from -- the site table, /etc/hosts, the name server's
+    # configuration -- and orphan the veth and the namespace it no longer knows
+    # about. Refuse rather than leave the machine in that state.
+    [ -d "$STATE" ] && die "a fixture is already up; run '$0 teardown' first"
     mkdir -p "$STATE" || die "cannot create $STATE"
     : > "$STATE/files"; : > "$STATE/dirs"
     : > "$STATE/nodes"; : > "$STATE/osimages"; : > "$STATE/services"