Resolve "memory leak in async code"

Closes #64

maestro/pool.c

@@ -1272,6 +1272,7 @@ mstro_status
 mstro_pool__demand_async_no_pm(mstro_cdo cdo, mstro_cdo_state new_state)
 {
 
+  assert(MSTRO_CDO_STATE_DEMANDED == new_state);
   // increase waiters by one
   return mstro_pool_cdo_waiters(cdo, 1);
 }
@@ -1706,6 +1707,8 @@ mstro_pool__demand_async_with_pm(mstro_cdo cdo, mstro_cdo_state new_state)
 {
   mstro_status status = MSTRO_UNIMPL;
 
+  assert(MSTRO_CDO_STATE_DEMANDED == new_state);
+
   /* tell pool manager it's urgent now */
   /* that will eventually kick off a transport occuring and filling in
    * a CDO OFFER that can be used to satisfy this demand. We'll be