update nixpkgs-unstable

- bitcoind 0.20.1 -> 0.21.0
  Manually create a wallet in the backup test because bitcoind
  does not create a default wallet anymore

- disable the failing elementsd build on unstable

pkgs/nixpkgs-pinned.nix

@@ -12,7 +12,7 @@ in
     sha256 = "1vjh0np1rlirbhhj9b2d0zhrqdmiji5svxh9baqq7r3680af1iif";
   };
   nixpkgs-unstable = fetch {
-    rev = "296793637b22bdb4d23b479879eba0a71c132a66";
-    sha256 = "0j09yih9693w5vjx64ikfxyja1ha7pisygrwrpg3wfz3sssglg69";
+    rev = "891f607d5301d6730cb1f9dcf3618bcb1ab7f10e";
+    sha256 = "1cr39f0sbr0h5d83dv1q34mcpwnkwwbdk5fqlyqp2mnxghzwssng";
   };
 }

test/pkgs-unstable.nix

@@ -4,10 +4,15 @@ let
   nbPkgs = import ../pkgs { inherit pkgs; };
   pkgsUnstable = with nbPkgs; [
     electrs
-    elementsd
     hwi
     joinmarket
     lightning-loop
+
+    ## elementsd fails with error
+    # test/key_properties.cpp:16:10: fatal error: rapidcheck/boost_test.h: No such file or directory
+    # 16 | #include <rapidcheck/boost_test.h>
+    #    |          ^~~~~~~~~~~~~~~~~~~~~~~~~
+    # elementsd
   ];
 in
 pkgs.writeText "pkgs-unstable" (pkgs.lib.concatMapStringsSep "\n" toString pkgsUnstable)

test/tests.nix

@@ -187,6 +187,7 @@ let testEnv = rec {
       services.bitcoind.regtest = true;
       systemd.services.bitcoind.postStart = mkAfter ''
         cli=${config.services.bitcoind.cli}/bin/bitcoin-cli
+        $cli createwallet "test"
         address=$($cli getnewaddress)
         $cli generatetoaddress 10 $address
       '';

test/tests.py

@@ -286,6 +286,9 @@ def _():
 # Impure: stops bitcoind (and dependent services)
 @test("backups")
 def _():
+    # For testing that bitcoind wallets are backed up
+    succeed("bitcoin-cli -named createwallet wallet_name=test blank=true >/dev/null")
+
     succeed("systemctl stop bitcoind")
     succeed("systemctl start duplicity")
     machine.wait_until_succeeds(log_has_string("duplicity", "duplicity.service: Succeeded."))
@@ -297,7 +300,7 @@ def _():
     )
     # Backup should include important files
     files = {
-        "bitcoind": "var/lib/bitcoind/wallet.dat",
+        "bitcoind": "var/lib/bitcoind/test/wallet.dat",
         "clightning": "var/lib/clightning/bitcoin/hsm_secret",
         "lnd": "secrets/lnd-seed-mnemonic",
         "joinmarket": "secrets/jm-wallet-seed",