Our normal import interfaces introduce keys with an effective timestamp of 0.

Importmulti introduces keys with a default effective timestamp of 'now'.

While documented it is highly surprising, especially because it contradicts the default on the rescan argument:

>     "rescan": <false>,         (boolean, optional, default: true) Stating if should rescan the blockchain after all imports

This means you can import a key and reasonably expect that it was rescanned ("I even set rescan true!") but have it not be rescanned, causing you to think the key had been unused and then you give it away and or destroy it and lose funds.

There are a number of other bugs in importmulti (mishandles pruning, needlessly forces the wallet to be unlocked when not importing private keys, etc.) which I am fixing, but I need feedback on this API issue.

Should the default become zero, with -1 special cased as 'now' or make timestamp mandatory? default it to the prune depth??

Should the result also tell us what it rescanned?
{
    /* Please, avoid using the word "pool" here in the RPC interface or help,
     * as users will undoubtedly confuse it with the other "memory pool"
     */
    if (request.fHelp || request.params.size() != 0)
        throw runtime_error(
            "getmemoryinfo\n"
            "Returns an object containing information about memory usage.\n"
            "\nResult:\n"
            "{\n"
            "  \"locked\": {               (json object) Information about locked memory manager\n"
            "    \"used\": xxxxx,          (numeric) Number of bytes used\n"
            "    \"free\": xxxxx,          (numeric) Number of bytes available in current arenas\n"
            "    \"total\": xxxxxxx,       (numeric) Total number of bytes managed\n"
            "    \"locked\": xxxxxx,       (numeric) Amount of bytes that succeeded locking. If this number is smaller than total, locking pages failed at some point and key data could be swapped to disk.\n"
            "    \"chunks_used\": xxxxx,   (numeric) Number allocated chunks\n"
            "    \"chunks_free\": xxxxx,   (numeric) Number unused chunks\n"
            "  }\n"
            "}\n"
            "\nExamples:\n"
            + HelpExampleCli("getmemoryinfo", "")
            + HelpExampleRpc("getmemoryinfo", "")
        );
    UniValue obj(UniValue::VOBJ);
    obj.push_back(Pair("locked", RPCLockedMemoryInfo()));
    return obj;
}
UniValue echo(const JSONRPCRequest& request)