publisher, deployer: report ssh failure instead of BrokenPipeError (0.9.8)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

srcpkgs/deployer/files/tests/test_core.py

@@ -1,3 +1,4 @@
+import os
 from pathlib import Path
 
 import pytest
@@ -175,3 +176,14 @@ def test_python_config_layout(tmp_path):
     plan.dest = "/home/user/app/docker/stack"
     plan.app = config.App(name="stack", kind="docker", src=str(tmp_path), dest="docker/stack")
     assert get("docker").config_items(plan) == [(".env", "/home/user/app/configs/docker/stack.env")]
+
+
+def test_ssh_exits_early(tmp_path, monkeypatch):
+    # ssh dies at once (e.g. unresolvable host): the broken pipe must surface as RemoteError with its message
+    fake = tmp_path / "ssh"
+    fake.write_text("#!/bin/sh\necho \"ssh: Could not resolve hostname\" >&2\nexit 255\n")
+    fake.chmod(0o755)
+    monkeypatch.setenv("PATH", f"{tmp_path}:{os.environ['PATH']}")
+    srv = config.Server(host="nohost.invalid", user="u")
+    with pytest.raises(remote.RemoteError, match="Could not resolve"):
+        remote.run(srv, "x" * 5_000_000, check=False)