commit 537918fef23ac0a2dae6644458aa52ea8e8b46df
Author: Jelmer Vernooĳ <jelmer@jelmer.uk>
Date:   Mon Nov 17 23:04:43 2025 +0000

    Add scary warning to 'brz fast-export'

diff --git a/breezy/plugins/fastimport/cmds.py b/breezy/plugins/fastimport/cmds.py
index 0f600147e9..0e7970cfd7 100644
--- a/breezy/plugins/fastimport/cmds.py
+++ b/breezy/plugins/fastimport/cmds.py
@@ -518,6 +518,7 @@ class cmd_fast_export(Command):
         Option("no-tags", help="Don't export tags"),
     ]
     encoding_type = "exact"
+    hidden = True
 
     def run(
         self,
@@ -537,8 +538,15 @@ class cmd_fast_export(Command):
     ):
         load_fastimport()
         from ...branch import Branch
+        from ...trace import warning
         from . import exporter
 
+        warning(
+            "the 'brz fast-export' command has known issues that can lead to "
+            "data loss. It has no tests and may be removed in future releases. "
+            "Use with caution!"
+        )
+
         if marks:
             import_marks = export_marks = marks
 
