diff -r a3ec6db36315 -r a8b17859684a mercurial/commands.py
--- a/mercurial/commands.py	Wed Aug 17 20:56:11 2016 -0700
+++ b/mercurial/commands.py	Wed Aug 17 20:57:15 2016 -0700
@@ -9,7 +9,6 @@
 
 import difflib
 import errno
-import operator
 import os
 import re
 import shlex
@@ -1860,51 +1859,6 @@
     with repo.wlock(False):
         return cmdutil.copy(ui, repo, pats, opts)
 
-@command('debugextensions', formatteropts, [], norepo=True)
-def debugextensions(ui, **opts):
-    '''show information about active extensions'''
-    exts = extensions.extensions(ui)
-    hgver = util.version()
-    fm = ui.formatter('debugextensions', opts)
-    for extname, extmod in sorted(exts, key=operator.itemgetter(0)):
-        isinternal = extensions.ismoduleinternal(extmod)
-        extsource = extmod.__file__
-        if isinternal:
-            exttestedwith = []  # never expose magic string to users
-        else:
-            exttestedwith = getattr(extmod, 'testedwith', '').split()
-        extbuglink = getattr(extmod, 'buglink', None)
-
-        fm.startitem()
-
-        if ui.quiet or ui.verbose:
-            fm.write('name', '%s\n', extname)
-        else:
-            fm.write('name', '%s', extname)
-            if isinternal or hgver in exttestedwith:
-                fm.plain('\n')
-            elif not exttestedwith:
-                fm.plain(_(' (untested!)\n'))
-            else:
-                lasttestedversion = exttestedwith[-1]
-                fm.plain(' (%s!)\n' % lasttestedversion)
-
-        fm.condwrite(ui.verbose and extsource, 'source',
-                 _('  location: %s\n'), extsource or "")
-
-        if ui.verbose:
-            fm.plain(_('  bundled: %s\n') % ['no', 'yes'][isinternal])
-        fm.data(bundled=isinternal)
-
-        fm.condwrite(ui.verbose and exttestedwith, 'testedwith',
-                     _('  tested with: %s\n'),
-                     fm.formatlist(exttestedwith, name='ver'))
-
-        fm.condwrite(ui.verbose and extbuglink, 'buglink',
-                 _('  bug reporting: %s\n'), extbuglink or "")
-
-    fm.end()
-
 @command('debugfileset',
     [('r', 'rev', '', _('apply the filespec on this revision'), _('REV'))],
     _('[-r REV] FILESPEC'))