[PATCH 1 of 2 STABLE] diffhelpers: add canstripcr=True to fix_newline

[Jun Wu]

Excerpts from Yuya Nishihara's message of 2017-04-26 20:39:30 +0900:
> [...]
> I have a patch set to get rid of the whole mess of pure/c-ext import hacks.
> Hopefully the copy-paste will die in 4.3.

Ah, I may have written something similar [1] yesterday. I guess your patches
may be cleaner as I didn't improve __init__.py.

[1]: https://bpaste.net/show/742e6c81af22

Given the fact that they will be solved soon, I think we may want to defer
the fix so there won't be a copy-paste.

> Sorry, I said the opposite thing. It should be old binary + new Mercurial.

I realized later. Thanks for clarification!