qa: finish the python3 port far enough to build the shared test chain

Follow-up to 5e0a70683, which got start_node() working. Three more
defects sat behind it:

- initialize_chain() builds the 4-node cache with its own daemon
  invocation, which 5e0a70683 did not touch. It therefore still omitted
  -regtest (so those cache nodes ran on MAINNET) and -asmap (so they
  refused to start at all). Every test that uses the cache -- which is
  most of the wallet suite -- died there.

- reindex.py and getblocktemplate_longpoll.py each carried a single
  python2 print statement, which is the whole reason they would not even
  parse under python3. Shebangs updated to match.

The suite still does not pass: initialize_chain hits a remaining py2
str+int concatenation, and getblocktemplate.py reaches a real test
assertion. Both are beyond this commit, but the harness now gets far
enough to start nodes, answer RPC and begin building the shared chain,
which it could not do before.

qa/rpc-tests/getblocktemplate_longpoll.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 # Copyright (c) 2016-2024 The Hush developers
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the GPLv3 software license, see the accompanying
@@ -52,7 +52,7 @@ class GetBlockTemplateLPTest(BitcoinTestFramework):
     '''
 
     def run_test(self):
-        print "Warning: this test will take about 70 seconds in the best case. Be patient."
+        print("Warning: this test will take about 70 seconds in the best case. Be patient.")
         self.nodes[0].generate(10)
         templat = self.nodes[0].getblocktemplate()
         longpollid = templat['longpollid']

qa/rpc-tests/reindex.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 # Copyright (c) 2014 The Bitcoin Core developers
 # Copyright (c) 2016-2024 The Hush developers
 # Released under the GPLv3
@@ -28,7 +28,7 @@ class ReindexTest(BitcoinTestFramework):
         wait_bitcoinds()
         self.nodes[0]=start_node(0, self.options.tmpdir, ["-debug", "-reindex", "-checkblockindex=1"])
         assert_equal(self.nodes[0].getblockcount(), 3)
-        print "Success"
+        print("Success")
 
 if __name__ == '__main__':
     ReindexTest().main()

qa/rpc-tests/test_framework/util.py

@@ -145,7 +145,13 @@ def initialize_chain(test_dir):
         # Create cache directories, run hushds:
         for i in range(4):
             datadir=initialize_datadir("cache", i)
-            args = [ os.getenv("BITCOIND", "dragonxd"), "-keypool=1", "-datadir="+datadir, "-discover=0" ]
+            # Same two requirements as start_node(): -regtest must be a command-line flag (the
+            # conf key is ignored, and without it this cache node runs on MAINNET), and -asmap
+            # must be absolute or dragonxd refuses to start.
+            args = [ os.getenv("BITCOIND", "dragonxd"), "-regtest", "-connect=0", "-keypool=1", "-datadir="+datadir, "-discover=0" ]
+            _am = os.path.join(os.path.dirname(os.path.abspath(__file__)), "../../../asmap.dat")
+            if os.path.exists(_am):
+                args.append("-asmap=" + os.path.realpath(_am))
             if i > 0:
                 args.append("-connect=127.0.0.1:"+str(p2p_port(0)))
             bitcoind_processes[i] = subprocess.Popen(args)