tst/test_maint.sh: pass null string to check_count for non-exact checks.

* Deal with a stricter bash in Ubuntu Hardy that won't shift non-existent
  things off the argument list.
* Use $NREPLICAS instead of $nreplicas, which happens to be defined
  but isn't the parameter we want.  Damn lack of scoping.

tst/test_maint.sh

@@ -295,10 +295,10 @@ sleep 120 # XXX wait longer?
 if [ $mode = "carbonite" ];
 then
     expect_norepairs || fail
-    check_counts $nreplicas exact && echo "OK"
+    check_counts $NREPLICAS exact && echo "OK"
 else
     expect_repairs || fail
-    check_counts $nreplicas && echo "OK"
+    check_counts $NREPLICAS "" && echo "OK"
 fi
 
 sleep 5
@@ -318,7 +318,7 @@ wait_stable && echo "OK" || fail
 
 echo "Waiting and checking after repair timers..."
 sleep 240
-check_counts $nreplicas && echo "OK" || echo "Blocks lost!"
+check_counts $NREPLICAS "" && echo "OK" || echo "Blocks lost!"
 expect_repairs || fail
 
 echo -n "Inserting $batchsize additional objects: "
@@ -337,10 +337,10 @@ sleep 180
 if [ $mode = "carbonite" ];
 then
     expect_norepairs || fail
-    check_counts $nreplicas exact && echo "OK"
+    check_counts $NREPLICAS exact && echo "OK"
 else
     expect_repairs || fail
-    check_counts $nreplicas && echo "OK"
+    check_counts $NREPLICAS "" && echo "OK"
 fi
 
 teardown