The configure script automatically detects all versions of Python and builds
the bindings for each found version. This is a problem when building outside
of a clean environment since the ports system can only build a package for one
Python flavor at a time. The found versions of Python are overridden by
environment variables set in the port Makefile.

--- configure.orig	2019-03-26 17:29:46 UTC
+++ configure
@@ -23851,6 +23851,10 @@ $as_echo "$as_me: WARNING:
 
 	fi
 
+	# Override the automatically found Pythons with the selected version from ports.
+	PYTHONS=$BSD_PYTHON
+	PYTHON_VERSIONS=$BSD_PYTHON_VERSION
+	
 	# Recover some values lost in the second attempt to find Python.
 	PYTHON="$(echo $PYTHONS | cut -d ' ' -f 1)"
 	PYTHON_VERSION="$(echo $PYTHON_VERSIONS | cut -d ' ' -f 1)"