Sieve pipes in the external test are broken

For some reason master is green, because hydra tested something else than the latest nixpkgs in the flake. But I cannot successfully run the external test on master right now.

imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: sieve: action pipe: running program: sa-learn-spam.sh
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh: Created
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh: Pass environment: USER=user1@example.com
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh: Pass environment: HOME=/var/vmail
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh: Pass environment: HOST=server
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh: Establishing connection
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh: Forked child process
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Connected to program
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Finished streaming payload to program
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Finished input to program
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Disconnected
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Waiting for program to finish after 8 msecs (timeout = 9992 msecs)
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Execution timed out after 10000 milliseconds: Sending TERM signal
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Child process ended
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Error: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Forcibly terminated with signal 15
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Debug: program exec:/nix/store/3yv9zxi9ls8w4vmp4sxmil30jj8n08kk-sieve-pipe-bins/sa-learn-spam.sh (1945): Destroy
imap(user1@example.com)<1944><cwCsXbw08JDAqAEB>: Error: sieve: failed to pipe message to program `sa-learn-spam.sh': refer to server log for more information. [2025-05-09 23:31:40]