From 5ffa915c9c36956f4cd7ca304e363d2060dc38a2 Mon Sep 17 00:00:00 2001
From: "Todd C. Miller" <Todd.Miller@sudo.ws>
Date: Fri, 16 Apr 2021 14:06:07 -0600
Subject: [PATCH] determine Python (3.10) version number correctly. from
 upstream automake

---
 configure    |  2 +-
 m4/python.m4 | 12 +++++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/configure b/configure
index d46c8025c..29c381183 100755
--- a/configure
+++ b/configure
@@ -19594,7 +19594,7 @@ if test ${am_cv_python_version+y}
 then :
   printf %s "(cached) " >&6
 else $as_nop
-  am_cv_python_version=`$PYTHON -c "import sys; sys.stdout.write(sys.version[:3])"`
+  am_cv_python_version=`$PYTHON -c "import sys; print('%u.%u' % sys.version_info[:2])"`
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $am_cv_python_version" >&5
 printf "%s\n" "$am_cv_python_version" >&6; }
diff --git a/m4/python.m4 b/m4/python.m4
index 16c2f4f1a..b2302baa3 100644
--- a/m4/python.m4
+++ b/m4/python.m4
@@ -1,7 +1,7 @@
 ## ------------------------                                 -*- Autoconf -*-
 ## Python file handling
 ## From Andrew Dalke
-## Updated by James Henstridge
+## Updated by James Henstridge and other contributors.
 ## ------------------------
 # Copyright (C) 1999-2020 Free Software Foundation, Inc.
 #
@@ -86,12 +86,14 @@ AC_DEFUN([AM_PATH_PYTHON],
     m4_default([$3], [AC_MSG_ERROR([no suitable Python interpreter found])])
   else
 
-  dnl Query Python for its version number.  Getting [:3] seems to be
-  dnl the best way to do this; it's what "site.py" does in the standard
-  dnl library.
+  dnl Query Python for its version number.  Although site.py simply uses
+  dnl sys.version[:3], printing that failed with Python 3.10, since the
+  dnl trailing zero was eliminated. So now we output just the major
+  dnl and minor version numbers, as numbers. Apparently the tertiary
+  dnl version is not of interest.
 
   AC_CACHE_CHECK([for $am_display_PYTHON version], [am_cv_python_version],
-    [am_cv_python_version=`$PYTHON -c "import sys; sys.stdout.write(sys.version[[:3]])"`])
+    [am_cv_python_version=`$PYTHON -c "import sys; print('%u.%u' % sys.version_info[[:2]])"`])
   AC_SUBST([PYTHON_VERSION], [$am_cv_python_version])
 
   dnl Use the values of $prefix and $exec_prefix for the corresponding