diff -r d5edb5d3a337 -r a4358f7345b4 mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Thu Feb 14 22:46:18 2019 -0800
+++ b/mercurial/debugcommands.py	Fri Jan 18 13:13:30 2019 -0800
@@ -1741,6 +1741,28 @@
             cmdutil.showmarker(fm, m, index=ind)
         fm.end()
 
+@command('debugp1copies',
+         [('r', 'rev', '', _('revision to debug'), _('REV'))],
+         _('[-r REV]'))
+def debugp1copies(ui, repo, **opts):
+    """dump copy information compared to p1"""
+
+    opts = pycompat.byteskwargs(opts)
+    ctx = scmutil.revsingle(repo, opts.get('rev'), default=None)
+    for dst, src in ctx.p1copies().items():
+        ui.write('%s -> %s\n' % (src, dst))
+
+@command('debugp2copies',
+         [('r', 'rev', '', _('revision to debug'), _('REV'))],
+         _('[-r REV]'))
+def debugp1copies(ui, repo, **opts):
+    """dump copy information compared to p2"""
+
+    opts = pycompat.byteskwargs(opts)
+    ctx = scmutil.revsingle(repo, opts.get('rev'), default=None)
+    for dst, src in ctx.p2copies().items():
+        ui.write('%s -> %s\n' % (src, dst))
+
 @command('debugpathcomplete',
          [('f', 'full', None, _('complete an entire path')),
           ('n', 'normal', None, _('show only normal files')),