Fix autoconf detection of python

This also fully honors the PYTHON_VERSION environment variable.

configure.ac

@@ -145,8 +145,10 @@ AC_CHECK_LIB(expat,main)
 
 dnl python
 [TEMP_CPPFLAGS="${CPPFLAGS}"]
-AM_PATH_PYTHON([2.5])
 AC_PYTHON_DEVEL([2.5])
+[PYTHON="python${PYTHON_VERSION}"]
+AX_PYTHON
+AM_PATH_PYTHON([2.5])
 [CPPFLAGS="${CPPFLAGS} ${PYTHON_CPPFLAGS}"]
 [LDFLAGS="${LDFLAGS} ${PYTHON_LDFLAGS}"]
 

m4/ac_python_module.m4

@@ -25,9 +25,11 @@
 #   and this notice are preserved.
 
 AC_DEFUN([AC_PYTHON_MODULE],[
-    if test -z $PYTHON;
+    if test -z $PYTHON_BIN;
     then
         PYTHON="python"
+    else
+        PYTHON=$PYTHON_BIN
     fi
     PYTHON_NAME=`basename $PYTHON`
     AC_MSG_CHECKING($PYTHON_NAME module: $1)

m4/ax_python.m4

@@ -58,7 +58,13 @@
 AC_DEFUN([AX_PYTHON],
 [AC_MSG_CHECKING(for python build information)
 AC_MSG_RESULT([])
-for python in python2.8 python2.7 python2.6 python2.5 python2.4 python2.3 python2.2 python2.1 python; do
+if test -z $PYTHON_VERSION
+then
+    python_list="python2.7 python2.6 python2.5 python2.4 python2.3 python2.2 python2.1 python"
+else
+    python_list="python$PYTHON_VERSION"
+fi
+for python in $python_list; do
 AC_CHECK_PROGS(PYTHON_BIN, [$python])
 ax_python_bin=$PYTHON_BIN
 if test x$ax_python_bin != x; then