INDY-156 POOL_UPGRADE txn unclear error message (hyperledger#197)

* added test and modified handler

* removed test_configReqHandler.py

* changed to InvalidClientRequest

* fixed test

sovrin_node/server/config_req_handler.py

@@ -64,6 +64,13 @@ def validate(self, req: Request, config=None):
             status = self.upgrader.statusInLedger(req.operation.get(NAME),
                                                   req.operation.get(VERSION))
 
+            if status == START and action == START:
+                raise InvalidClientRequest(
+                    req.identifier,
+                    req.reqId,
+                    "Upgrade '{}' is already scheduled".format(
+                        req.operation.get(NAME)))
+
             r, msg = Authoriser.authorised(POOL_UPGRADE, ACTION, originRole,
                                            oldVal=status, newVal=action)
             if not r:

sovrin_node/test/upgrade/test_pool_upgrade_reject.py

@@ -5,7 +5,7 @@
 from sovrin_client.test.helper import checkRejects, checkNacks
 from sovrin_common.constants import CANCEL, \
     ACTION
-from sovrin_node.test.upgrade.helper import sendUpgrade, \
+from sovrin_node.test.upgrade.helper import sendUpgrade, ensureUpgradeSent, \
     bumpedVersion
 from stp_core.loop.eventually import eventually
 
@@ -42,4 +42,10 @@ def testNonTrustyCannotCancelUpgrade(looper, validUpgradeSent,
     looper.run(eventually(checkRejects, stClient, req.reqId,
                           'cannot do'))
 
+def test_accept_then_reject_upgrade(looper, trustee, trusteeWallet, validUpgradeSent, validUpgrade):
+    validUpgrade2 = deepcopy(validUpgrade)
+    _, req = sendUpgrade(trustee, trusteeWallet, validUpgrade2)
+    timeout = plenumWaits.expectedReqNAckQuorumTime()
+    looper.run(eventually(checkRejects, trustee, req.reqId,
+                          'InvalidClientRequest', retryWait=1, timeout=timeout))