fix bitcoin issue #19928 also for knots

This patch ̶s̶h̶o̶u̶l̶d̶ fix the issue reported in https://github.com/bitcoin/bitcoin/issues/19928

diff --git a/src/wallet/walletutil.cpp b/src/wallet/walletutil.cpp
index 39520267c..a7f7eb819 100644
--- a/src/wallet/walletutil.cpp
+++ b/src/wallet/walletutil.cpp
@@ -63,7 +63,9 @@ std::vector<fs::path> ListWalletDir()
     const fs::path data_dir = GetDataDir();
     const fs::path blocks_dir = GetBlocksDir();

-    const size_t offset = wallet_dir.string().size() + 1;
+    // account for possible trailing backslash, since we might have only boost 1.47 we could not use fs::relative
+    const size_t offset = (wallet_dir.string().back() != '/') ? wallet_dir.string().size() + 1 : wallet_dir.parent_path().string().size() + 1;
+
     std::vector<fs::path> paths;
     boost::system::error_code ec;
     boost::system::error_code eci;

edit@saibato ̶S̶t̶i̶l̶l̶ ̶d̶r̶a̶f̶t̶:̶ ̶ ̶W̶i̶l̶l̶ ̶d̶o̶ ̶o̶n̶l̶y̶ ̶p̶a̶r̶t̶l̶y̶ ̶t̶h̶e̶ ̶j̶o̶b̶,̶ ̶h̶m̶m̶.̶.̶.̶

If a user would add a trailing '/' or more e.g. '////' to the -datadir path, listwalletdir would strip one char of the wallename with every open. This will happen if there is no wallets subdir e.g an older node or the wallets dir would have been renamed

bitcoinknots / bitcoin

fix bitcoin issue #19928 also for knots #28