For reasons I do not really grok, this PR changes the timing behavior of the
functional tests to reliably expose a deadlock in the claimpegin RPC that has
existed since the 0.17 rebase.
The mechanism is: in `claimpegin` in src/wallet/rpcwallet.cpp:5873, we call
`AcceptToMemoryPoolWorker`. This requires cs_main to be locked, which it is
not (contrast Core's `testmempoolaccept` RPC, which similarly calls
`AcceptToMemoryPoolWorker` from the RPC thread, and locks cs_main immediately
before).
We do *say* that it is locked, in the `LockAssertion` one the line above, but
this was added in ad3d496d78 during the 0.17
rebase (PR #620), apparently to shut up some linter on OSX, and as near as I
can tell it was never true.
Anyway, `AcceptToMemoryPoolWorker` calls through a couple layers which assume
cs_main is locked, to `AcceptSingleTransaction`, which locks m_pool.cs on line
src/validation.cpp:1101. It then calls `PreChecks`, which on line 784 calls
::ChainActive(), which _actually_ locks cs_main, though only briefly. This
line is the deadlock, because we locked m_pool.cs followed by cs_main...
...meanwhile, in src/net_processing.cpp, we lock cs_main at the top of the
`PeerLogicValidation::SendMessages` loop (src/net_processing.cpp:3628). In the
same loop, in the `feefilter` message processing, we call CTxMemPool::GetMinFee
(src/net_processing.cpp:4137), which locks m_pool.cs. Deadlock.
Anyway, that explains the change to locking behavior that I added to an
otherwise test-only PR.
For the sake of getting on with the rebase, I just re-added all of bitcoin-common
and bitcoin-server to bitcoin-wallet. We should revisit and try to clean this
up in future, to try to achieve the same separation that Core has.
This is another one where git sorta mangled .travis.yml and I didn't bother
trying to sort it out. Just took the original code for every conflict. We'll
pretty-much have to redo the CI post-rebase.
