Remove usehd option and warn when it is used

Removed the -usehd option so wallets cannot be made to be non-hd
anymore. A warning will be displayed when the option is set.

test/functional/keypool-topup.py

@@ -23,7 +23,7 @@ class KeypoolRestoreTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 2
-        self.extra_args = [['-usehd=0'], ['-usehd=1', '-keypool=100', '-keypoolmin=20']]
+        self.extra_args = [[], ['-keypool=100', '-keypoolmin=20']]
 
     def run_test(self):
         self.tmpdir = self.options.tmpdir

test/functional/wallet-hd.py

@@ -15,17 +15,11 @@ class WalletHDTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 2
-        self.extra_args = [['-usehd=0'], ['-usehd=1', '-keypool=0']]
+        self.extra_args = [[], ['-keypool=0']]
 
     def run_test (self):
         tmpdir = self.options.tmpdir
 
-        # Make sure can't switch off usehd after wallet creation
-        self.stop_node(1)
-        self.assert_start_raises_init_error(1, ['-usehd=0'], 'already existing HD wallet')
-        self.start_node(1)
-        connect_nodes_bi(self.nodes, 0, 1)
-
         # Make sure we use hd, keep masterkeyid
         masterkeyid = self.nodes[1].getwalletinfo()['hdmasterkeyid']
         assert_equal(len(masterkeyid), 40)

test/functional/wallet.py

@@ -10,10 +10,9 @@ class WalletTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 4
         self.setup_clean_chain = True
-        self.extra_args = [['-usehd={:d}'.format(i%2==0)] for i in range(4)]
 
     def setup_network(self):
-        self.add_nodes(4, self.extra_args)
+        self.add_nodes(4)
         self.start_node(0)
         self.start_node(1)
         self.start_node(2)