diff -r 9d4f09bfe3ec -r 814e080a1215 mercurial/commands.py
--- a/mercurial/commands.py	Wed Apr 04 19:17:22 2018 -0700
+++ b/mercurial/commands.py	Wed Apr 04 21:09:47 2018 -0700
@@ -3492,6 +3492,8 @@
             raise error.Abort(_("can't specify a revision with --all"))
 
         res = []
+        # TODO this is a massive layering violation. It assumes the repo is
+        # backed by revlogs with a well-defined naming scheme.
         prefix = "data/"
         suffix = ".i"
         plen = len(prefix)