Steps to reproduce:
- Create an empty data directory with a testnet bitcoin.conf; e.g. mkdir /tmp/d echo "testnet=1" >> /tmp/d/bitcoin.conf echo "rpcuser=abc" >> /tmp/d/bitcoin.conf echo "rpcpassword=def" >> /tmp/d/bitcoin.conf
- Run Bitcoin-Qt with -datadir=/tmp/d
You get a nice green splashscreen, BUT a wallet.dat and blockchain files directly in /tmp/d, not in /tmp/d/testnet3/
bitcoind behaves correctly.