[MERGE][#202331] optionally show diff in log

[Ian Clatworthy]

John Arbash Meinel wrote:
> John Arbash Meinel has voted tweak.

Thanks for the review.

> I'm fine with the flag, as it seems to be compatible with other
> implementations. But I'm thinking we probably *don't* want to indent the
> diffs themselves.
> 
> The main reason is that I think it would allow you to feed "bzr log -p |
> patch -p0".

I've switched off indenting for the top level of long format. I'm not
sure whether switching it off for nested revisions makes sense and doing
so certainly makes it look much uglier. If someone really wants that,
we ought to either:

* direct them to a better way of doing things (e.g. merge directives)
* add a new log format (flat say)

The other question is if we now need to add the flag for
> prefixes/no-prefixes. Which, unfortunately, collides with 'bzr diff -p'
> but we could only expose the 'bzr log -p --prefix a:b' sort of thing.

If someone wants prefix support added to log, it won't be hard to do
as a follow-on patch. The single revision case is covered now by diff
of course, so it's only if they want a series of patches that it becomes
an issue. I think using 'bzr log -p --prefix a:b' would be fine then.

Ian C.