This little diff should fix many cases instead fixing every by hand.
What do you think?
Index: python.port.mk
===================================================================
RCS file: /cvs/ports/lang/python/python.port.mk,v
retrieving revision 1.120
diff -u -p -r1.120 python.port.mk
--- python.port.mk 11 Feb 2020 11:45:31 -0000 1.120
+++ python.port.mk 30 Mar 2020 16:49:57 -0000
@@ -190,6 +190,9 @@ CONFIGURE_ENV += PYTHON="${MODPY_BIN}"
.if ${CONFIGURE_STYLE:Mgnu}
CONFIGURE_ENV += ac_cv_prog_PYTHON="${MODPY_BIN}" \
ac_cv_path_PYTHON="${MODPY_BIN}"
+.elif ${CONFIGURE_STYLE:Mcmake}
+# https://cmake.org/cmake/help/latest/module/FindPythonInterp.html
+CONFIGURE_ARGS += -DPYTHON_EXECUTABLE=${MODPY_BIN}
.endif
MODPY_CMD = cd ${WRKSRC} && ${SETENV} ${MAKE_ENV} \
