btcd: Nondeterministic test failure - "unable to setup test chain: the client has been disconnected"

When I run the tests, sometimes they pass, but about 2/3 of the time they fail like this:

unable to setup test chain:  the client has been disconnected
FAIL    github.com/btcsuite/btcd        0.633s
ok      github.com/btcsuite/btcd/addrmgr        0.187s
ok      github.com/btcsuite/btcd/blockchain     0.558s
ok      github.com/btcsuite/btcd/blockchain/indexers    0.063s
ok      github.com/btcsuite/btcd/btcec  2.442s
ok      github.com/btcsuite/btcd/btcjson        0.027s
ok      github.com/btcsuite/btcd/chaincfg       0.010s
ok      github.com/btcsuite/btcd/chaincfg/chainhash     0.032s
?       github.com/btcsuite/btcd/cmd/addblock   [no test files]
?       github.com/btcsuite/btcd/cmd/btcctl     [no test files]
?       github.com/btcsuite/btcd/cmd/findcheckpoint     [no test files]
?       github.com/btcsuite/btcd/cmd/gencerts   [no test files]
ok      github.com/btcsuite/btcd/database       0.079s
?       github.com/btcsuite/btcd/database/cmd/dbtool    [no test files]
ok      github.com/btcsuite/btcd/database/ffldb 1.705s
ok      github.com/btcsuite/btcd/database/internal/treap        0.047s
?       github.com/btcsuite/btcd/limits [no test files]
ok      github.com/btcsuite/btcd/mempool        0.112s
?       github.com/btcsuite/btcd/mining [no test files]
ok      github.com/btcsuite/btcd/peer   0.039s
unable to setup test chain:  the client has been disconnected
FAIL    github.com/btcsuite/btcd/rpctest        0.538s
ok      github.com/btcsuite/btcd/txscript       0.653s
ok      github.com/btcsuite/btcd/wire   0.586s