ticketbuyer does not honor ticketbuyer.votingaccount setting (since v2.0.5)

[hb9xar]

Hi there,

Setup:

• 1x PoS staking wallet with 2x independent voting wallet
• Account from voting wallet has been imported to staking wallet using getmasterpubkey/importxpub
• No mixing is active
• staking wallet is configured with "ticketbuyer.votingaccount=XXXX"

Starting with dcrwallet release-v2.0.5, the internal ticket buyer does no longer honor the ticketbuyer.votingaccount config option for buying tickets, but instead uses the PurchaseAccount to derive the ticket address. As a result, the tickets are "lost" (are sent to wrong wallet and no voting is done).

It seems to have been introduced with commit 5cd89f5 #2416 "wallet: Use purchase acct for voting if not mixing"
Commit Comment:
"In the case where mixing is disabled and no voting account has been set,
the purchase account should be used as a fallback to derive a ticket
voting address."

The description sounds OK, but the actual code change does only consider votingaddress and not votingaccount and finally falls back to PurchaseAccount.

Expected behavior:

• if votingaccount is set, it should be honored and used for ticket purchases
• if votingaddress is set, it should be honored - as it seems that votingaddress is going to be eliminated (no longer present in "master") it may not need to be considered
• fallback to PurchaseAccount

Looking at the code (I'm not fluent in Go), there seems to be a way to force using the votingaccount (UseVotingAccount boolean), but it does not seem to be used anywhere - I did not find a place inside dcrwallet where this boolean is actually set.
Also I believe this issue only shows up if NO mixing is done (-> wallet/createtx.go:1708) as mixing uses the same code path to get the ticket address as with UseVotingAccount=true.