Finished the edge cases for dropping and intransitive unlocking.

adventure/tests/vignettes.txt

@@ -695,14 +695,42 @@ THE PLANT HAS EXCEPTIONALLY DEEP ROOTS AND CANNOT BE PULLED FREE.
 >>> get(oil)
 YOU HAVE NOTHING IN WHICH TO CARRY IT.
 <BLANKLINE>
-
->>> quiet(restart(), get(bottle), goto(24))
+>>> quiet(goto(3), get(bottle), goto(24))
 >>> get(oil)
 YOUR BOTTLE IS ALREADY FULL.
 <BLANKLINE>
 >>> get(bottle)
 YOU ARE ALREADY CARRYING IT!
 <BLANKLINE>
+>>> drop(oil)
+YOU AREN'T CARRYING IT!
+<BLANKLINE>
+>>> drop(water)
+OK
+<BLANKLINE>
+>>> look
+YOU ARE AT THE BOTTOM OF THE EASTERN PIT IN THE TWOPIT ROOM.  THERE IS
+A SMALL POOL OF OIL IN ONE CORNER OF THE PIT.
+<BLANKLINE>
+THERE IS A BOTTLE OF WATER HERE.
+<BLANKLINE>
+
+>>> restart(room=94, objects=[oyster])
+>>> look
+YOU ARE AT ONE END OF AN IMMENSE NORTH/SOUTH PASSAGE.
+<BLANKLINE>
+THE WAY NORTH IS BARRED BY A MASSIVE, RUSTY, IRON DOOR.
+<BLANKLINE>
+THERE IS AN ENORMOUS OYSTER HERE WITH ITS SHELL TIGHTLY CLOSED.
+<BLANKLINE>
+>>> unlock                      # two unlockable objects are present
+UNLOCK WHAT?
+<BLANKLINE>
+>>> quiet(s)
+>>> unlock                      # no unlockable objects also cause a problem
+THERE IS NOTHING HERE WITH A LOCK!
+<BLANKLINE>
+
 
 
 todo: test plant2 in repository