--- a/doc/Makefile	Wed Apr 03 11:21:27 2019 -0700
+++ b/doc/Makefile	Thu Apr 04 19:06:48 2019 +0200
@@ -6,7 +6,7 @@
 PREFIX=/usr/local
 MANDIR=$(PREFIX)/share/man
 INSTALL=install -c -m 644
-PYTHON=python
+PYTHON?=python
 RSTARGS=
 
 export HGENCODING=UTF-8