patch 8.0.0251: not easy to select Python 2 or 3
Problem: It is not so easy to write a script that works with both Python 2
and Python 3, even when the Python code works with both.
Solution: Add 'pyxversion', :pyx, etc. (Marc Weber, Ken Takata)
diff --git a/src/userfunc.c b/src/userfunc.c
index 372c9bb..6a6cc06 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -2102,7 +2102,9 @@
arg = skipwhite(skiptowhite(p));
if (arg[0] == '<' && arg[1] =='<'
&& ((p[0] == 'p' && p[1] == 'y'
- && (!ASCII_ISALPHA(p[2]) || p[2] == 't'))
+ && (!ASCII_ISALNUM(p[2]) || p[2] == 't'
+ || ((p[2] == '3' || p[2] == 'x')
+ && !ASCII_ISALPHA(p[3]))))
|| (p[0] == 'p' && p[1] == 'e'
&& (!ASCII_ISALPHA(p[2]) || p[2] == 'r'))
|| (p[0] == 't' && p[1] == 'c'