diff -r bd0de73cf810 -r 0b475b0b0344 mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Fri Nov 22 20:12:10 2019 -0800
+++ b/mercurial/debugcommands.py	Fri Nov 22 20:27:09 2019 -0800
@@ -13,6 +13,7 @@
 import errno
 import operator
 import os
+import platform
 import random
 import re
 import socket
@@ -1487,6 +1488,11 @@
         pycompat.sysexecutable or _(b"unknown"),
     )
     fm.write(
+        b'pythonimplementation',
+        _(b"checking Python implementation (%s)\n"),
+        pycompat.sysbytes(platform.python_implementation()),
+    )
+    fm.write(
         b'pythonver',
         _(b"checking Python version (%s)\n"),
         (b"%d.%d.%d" % sys.version_info[:3]),