* Handle the unlikely case where a derivation has no dependencies at

all.

src/libstore/build.cc

@@ -887,6 +887,9 @@ void DerivationGoal::outputsSubstituted()
     foreach (PathSet::iterator, i, drv.inputSrcs)
         addWaitee(worker.makeSubstitutionGoal(*i));
 
+    if (waitees.empty()) /* to prevent hang (no wake-up event) */
+        inputsRealised();
+    else
         state = &DerivationGoal::inputsRealised;
 }