Most recent failure [on master](https://cirrus-ci.com/task/6073953614561280) (https://github.com/bitcoin/bitcoin/commit/567670bec5ecf9bc252e91370382be53fd81ccee):
```bash
 test  2021-06-23T11:18:18.969000Z TestFramework.node0 (DEBUG): Node stopped 
 test  2021-06-23T11:18:18.969000Z TestFramework.bitcoincli (DEBUG): Running bitcoin-cli ['-rpcwait', '-rpcwaittimeout=5', 'echo'] 
 test  2021-06-23T11:18:23.001000Z TestFramework (ERROR): Assertion failed 
                                   Traceback (most recent call last):
                                     File "/tmp/cirrus-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 128, in main
                                       self.run_test()
                                     File "/tmp/cirrus-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/interface_bitcoin_cli.py", line 257, in run_test
                                       assert_greater_than_or_equal(time.time(), start_time + 5)
                                     File "/tmp/cirrus-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/test_framework/util.py", line 61, in assert_greater_than_or_equal
                                       raise AssertionError("%s < %s" % (str(thing1), str(thing2)))
                                   AssertionError: 1624447103.0015192 < 1624447103.969648
 test  2021-06-23T11:18:23.004000Z TestFramework (DEBUG): Closing down network thread 
 test  2021-06-23T11:18:23.055000Z TestFramework (INFO): Stopping nodes 
```
std::string strRequest = rh->PrepareRequest(strMethod, args).write() + "\n";
    struct evbuffer* output_buffer = evhttp_request_get_output_buffer(req.get());
    assert(output_buffer);
    evbuffer_add(output_buffer, strRequest.data(), strRequest.size());
    
    std::string endpoint = "/";
    if (rpcwallet) {
        char* encodedURI = evhttp_uriencode(rpcwallet->data(), rpcwallet->size(), false);
        if (encodedURI) {
            endpoint = "/wallet/" + std::string(encodedURI);
            free(encodedURI);
        } else {
            throw CConnectionFailed("uri-encode failed");
        }
    }
    int r = evhttp_make_request(evcon.get(), req.get(), EVHTTP_REQ_POST, endpoint.c_str());
    req.release(); 
    if (r != 0) {
        throw CConnectionFailed("send http request failed");
    }
    event_base_dispatch(base.get());
    if (response.status == 0) {
        std::string responseErrorMessage;
        if (response.error != -1) {
            responseErrorMessage = strprintf(" (error code %d - \"%s\")", response.error, http_errorstring(response.error));
        }
        throw CConnectionFailed(strprintf("Could not connect to the server %s:%d%s\n\nMake sure the bitcoind server is running and that you are connecting to the correct RPC port.", host, port, responseErrorMessage));
    } else if (response.status == HTTP_UNAUTHORIZED) {
        if (failedToGetAuthCookie) {
            throw std::runtime_error(strprintf(