bug#30616: automake-1.16: aclocal is unable to process AM_PATH_PYTHON with variable as value

http://lists.gnu.org/archive/html/bug-automake/2018-02/msg00012.html

--- a/m4/python.m4
+++ b/m4/python.m4
@@ -36,24 +36,12 @@ AC_DEFUN([AM_PATH_PYTHON],
  [
   dnl Find a Python interpreter.  Python versions prior to 2.0 are not
   dnl supported. (2.0 was released on October 16, 2000).
-  m4_define_default([am_py_min_ver], m4_ifval([$1], [$1], [2.0]))
-  dnl The arbitrary default maximum version.
-  m4_define_default([am_py_max_ver], [4.0])
-
+  dnl FIXME: Remove the need to hard-code Python versions here.
   m4_define_default([_AM_PYTHON_INTERPRETER_LIST],
-    [[python] \
-     dnl If we want some Python 2 versions (min version <= 2.7),
-     dnl also search for "python2".
-     m4_if(m4_version_compare(am_py_min_ver, [2.8]), [-1], [python2], []) \
-     [python3] \
-     dnl Construct a comma-separated list of interpreter names (python2.6,
-     dnl python2.7, etc). We only care about the first 3 characters of the
-     dnl version strings (major-dot-minor; not
-     dnl major-dot-minor-dot-bugfix[-dot-whatever])
-     m4_foreach([py_ver],
-       m4_esyscmd_s(seq -s[[", "]] -f["[[%.1f]]"] m4_substr(am_py_max_ver, [0], [3]) -0.1 m4_substr(am_py_min_ver, [0], [3])),
-       dnl Remove python2.8 and python2.9 since they will never exist
-       [m4_bmatch(py_ver, [2.[89]], [], [python]py_ver)])])
+[python python2 python3 python3.9 python3.8 python3.7 python3.6 dnl
+ python3.5 python3.4 python3.3 python3.2 python3.1 python3.0 dnl
+ python2.7 python2.6 python2.5 python2.4 python2.3 python2.2 dnl
+ python2.1 python2.0])
 
   AC_ARG_VAR([PYTHON], [the Python interpreter])