makefile: use Python 3 by default when building docs as well
I copied the snippet defining `PYTHON` from the root Makefile.
Differential Revision: https://phab.mercurial-scm.org/D10251
#!/usr/bin/env python3
#
# A portable replacement for 'seq'
#
# Usage:
# seq STOP [1, STOP] stepping by 1
# seq START STOP [START, STOP] stepping by 1
# seq START STEP STOP [START, STOP] stepping by STEP
from __future__ import absolute_import, print_function
import os
import sys
try:
import msvcrt
msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
pass
if sys.version_info[0] >= 3:
xrange = range
start = 1
if len(sys.argv) > 2:
start = int(sys.argv[1])
step = 1
if len(sys.argv) > 3:
step = int(sys.argv[2])
stop = int(sys.argv[-1]) + 1
for i in xrange(start, stop, step):
print(i)