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

[Jun Wu]

Excerpts from Augie Fackler's message of 2017-04-25 18:20:06 -0400:
> Valid point. For now, let's preserve that invariant - Jun, can you make
> sure v2 has a graceful degradation path if it gets an old .so?

My understanding is while reasonable, we try to maintain compatibility in
both directions. i.e. it's a best-effort.

For this particular fix, If we enforce that rule, it means we have to use a
new method name, and copy paste hundreds of lines, *and* have dead code in
the repo. I don't think that's a good thing. So I'm not going to do that.
But maybe other people have different opinions, or a smarter way to fix this
without copy-paste.

> 
> Thanks!