[MERGE] Fix #175520 by implementing a --deep option for log

[Ian Clatworthy]

Robert Collins wrote:
> On Wed, 2009-01-14 at 13:29 +1000, Ian Clatworthy wrote:
>>
>> I'm happy to spend some more time thinking/discussing the UI
>> layer but I think it's worth extending the internals in this
>> direction as a patch now. The first application can be extending
>> log to support multiple FILE arguments, not just one.

> Internals leak, and ui can drive internals - so in short I'm saying,
> lets not add a file id based ui option unless thats actually what is
> needed.
> 
> AIUI vincent wants to support a user that needs to log a deleted path;
> neither file ids in the UI, nor multiple ids in the log core are needed
> to do that *as I understand the problem*.

So here's another UI alternative: add a list option to log with
the values of --current, --last, --once. These would control how
file-id lookup is done:

* --current - consult the current inventory
* --last - search until you find one
* --once - search all of history

Initially we could support just --current and --last. We'll need
multiple id support in the core of log before --once is added,
assuming we agree that the right behaviour is to union-log
against the set of file-ids that once represented a file of that
name.

While I'm at it, here are some thoughts on "log DIR". By default,
we should just log what happened to the directory object. To see
what happened to each of the current children, "log --children DIR".
(Again, that will need multiple id support.) To see what happened
to files that were once in DIR, "log --children --once DIR" say.

Ian C.