inline all messages

zfs_backup/commands/zfs.py

@@ -6,7 +6,6 @@ from subprocess import Popen
 from .. import Pool
 from ._core import CommandInterface
 from ..dataset import Dataset
-from ..messages import SAME_DATASET
 from ..misc import assert_type
 from ..snapshot import Snapshot
 from ..zfs_path import ZFSPath
@@ -90,7 +89,9 @@ class ZFS(CommandInterface):
                 f"Cannot send stream, object is not a Snapshot: {snapshot}",
             )
         if old_snapshot.dataset != new_snapshot.dataset:
-            raise ValueError(SAME_DATASET)
+            raise ValueError(
+                "Cannot send incremental snapshots if start and end snapshot are not based on the same dataset"
+            )
         if old_snapshot.newer_than(new_snapshot):
             raise ValueError("Old snapshot is newer than new snapshot.")
         if old_snapshot == new_snapshot: