test checkout of file lacking trailing \n over pserver protocol

This test reproduces the bug fixed in
commit d3b3344b where our custom cvs
client would fail to check out a file which lacks a trailing newline
from a remote CVS server.

The error triggered by the test without the fix in place is:

CVSProtocolError: Overlong response from CVS server:
b'delta with no trailing eolok\n'

swh/loader/cvs/tests/test_loader.py

@@ -269,3 +269,54 @@ def test_loader_cvs_visit_pserver(swh_storage, datadir, tmp_path):
     }
 
     check_snapshot(RUNBABY_SNAPSHOT, loader.storage)
+
+
+GREEK_SNAPSHOT3 = Snapshot(
+    id=hash_to_bytes("cd801546b0137c82f01b9b67848ba8261d64ebbb"),
+    branches={
+        b"HEAD": SnapshotBranch(
+            target=hash_to_bytes("14980990790ce1921db953c4c9ae03dd8861e8d6"),
+            target_type=TargetType.REVISION,
+        )
+    },
+)
+
+
+def test_loader_cvs_visit_pserver_no_eol(swh_storage, datadir, tmp_path):
+    """Visit to CVS pserver with file that lacks trailing eol"""
+    archive_name = "greek-repository3"
+    extracted_name = "greek-repository"
+    archive_path = os.path.join(datadir, f"{archive_name}.tgz")
+    repo_url = prepare_repository_from_archive(archive_path, extracted_name, tmp_path)
+    repo_url += "/greek-tree"  # CVS module name
+
+    # Ask our cvsclient to connect via the 'cvs server' command
+    repo_url = "fake://" + repo_url[7:]
+
+    loader = CvsLoader(
+        swh_storage, repo_url, cvsroot_path=os.path.join(tmp_path, archive_name)
+    )
+
+    assert loader.load() == {"status": "eventful"}
+
+    assert_last_visit_matches(
+        loader.storage,
+        repo_url,
+        status="full",
+        type="cvs",
+        snapshot=GREEK_SNAPSHOT3.id,
+    )
+
+    stats = get_stats(loader.storage)
+    assert stats == {
+        "content": 9,
+        "directory": 23,
+        "origin": 1,
+        "origin_visit": 1,
+        "release": 0,
+        "revision": 8,
+        "skipped_content": 0,
+        "snapshot": 8,
+    }
+
+    check_snapshot(GREEK_SNAPSHOT3, loader.storage)