--- a/mercurial/debugcommands.py	Tue Jul 23 14:36:38 2019 -0400
+++ b/mercurial/debugcommands.py	Tue Jul 23 14:37:51 2019 -0400
@@ -1383,6 +1383,11 @@
     fm.condwrite(err, 'usernameerror', _("checking username...\n %s\n"
         " (specify a username in your configuration file)\n"), err)
 
+    for name, mod in extensions.extensions():
+        handler = getattr(mod, 'debuginstall', None)
+        if handler is not None:
+            problems += handler(ui, fm)
+
     fm.condwrite(not problems, '',
                  _("no problems detected\n"))
     if not problems: