Fix seed_simulator=0 in the quantum instance

qiskit/aqua/quantum_instance.py

@@ -146,7 +146,7 @@ def __init__(self,
                                 'but you specified {}'.format(max_shots, shots))
 
         run_config = RunConfig(shots=shots, max_credits=max_credits)
-        if seed_simulator:
+        if seed_simulator is not None:
             run_config.seed_simulator = seed_simulator
 
         self._run_config = run_config

releasenotes/notes/qi-seed-simulator-757f88ec183082f7.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Previously, setting `seed_simulator=0` in the `QuantumInstance` did not set 
+    any seed. This was only affecting the value 0. This has been fixed.

test/aqua/operators/legacy/test_tpb_grouped_weighted_pauli_operator.py

@@ -30,7 +30,7 @@ class TestTPBGroupedWeightedPauliOperator(QiskitAquaTestCase):
 
     def setUp(self):
         super().setUp()
-        seed = 0
+        seed = 1
         aqua_globals.random_seed = seed
 
         self.num_qubits = 3

test/aqua/operators/legacy/test_weighted_pauli_operator.py

@@ -34,7 +34,7 @@ class TestWeightedPauliOperator(QiskitAquaTestCase):
 
     def setUp(self):
         super().setUp()
-        seed = 0
+        seed = 3
         aqua_globals.random_seed = seed
 
         self.num_qubits = 3