a 👍 I'm also interested in that.

Since there's a lot of Jinja work going on at the moment, maybe someone can merge this? :D.

Is it intentional/expected that keep_trailing_newline is only effective when passed into the constructor, and not when invoking render()?

For example, I have a template file that has a trailing newline:

>>> from jinja2 import Template
>>> from os.path import abspath, expanduser
>>> data = open(abspath(expanduser("~/jinjatest.txt"))).read()
>>> print "[%s]" % data
[line 1
line 2
]

When it gets rendered, the newline is removed:

>>> template = Template(data)
>>> print "[%s]" % template.render()
[line 1
line 2]

When rendering with keep_trailing_newline=True it is also removed:

>>> print "[%s]" % template.render(keep_trailing_newline=True)
[line 1
line 2]

But if I pass keep_trailing_newline=True when constructing the Template, it works as expected:

>>> template = Template(data, keep_trailing_newline=True)
>>> print "[%s]" % template.render()
[line 1
line 2
]