--- a/mercurial/commands.py	Thu Feb 02 10:04:34 2017 +0100
+++ b/mercurial/commands.py	Thu Feb 02 10:04:55 2017 +0100
@@ -1854,17 +1854,6 @@
     with repo.wlock(False):
         return cmdutil.copy(ui, repo, pats, opts)
 
-@command('debugsub',
-    [('r', 'rev', '',
-     _('revision to check'), _('REV'))],
-    _('[-r REV] [REV]'))
-def debugsub(ui, repo, rev=None):
-    ctx = scmutil.revsingle(repo, rev, None)
-    for k, v in sorted(ctx.substate.items()):
-        ui.write(('path %s\n') % k)
-        ui.write((' source   %s\n') % v[0])
-        ui.write((' revision %s\n') % v[1])
-
 @command('debugsuccessorssets',
     [],
     _('[REV]'))