[MERGE] Let find_previous_heads take a repository.

[Johan Rydberg]

Aaron Bentley <aaron.bentley at utoronto.ca> writes:

>> Personally I would not reject the idea of having a get_versioned_file
>> method in Repository, _as long as_ the user of it is well aware that
>> it may not implement the whole VersionedFile API.  I'm afraid some may
>> be tempted to use it instead of for example CommitBuilder to add new
>> texts to a file.
>
> I'm not sure why that's such a bad thing.  If you're committing a
> revision, it probably makes sense to use CommitBuilder.  If you're
> adding texts for another reason, (importing, upgrading, installing a
> bundle, data-recovery), it may not.

Because some formats may not group changes on per-file basis.  Think
Subversions fsfs format.  For such history formats, implementing phony
stores and VersionedFile-implementations is just an obstacle.

jelmer's subversion plugin has just this; FakeFileWeave, FakeFileStore
and FakeInventoryWeave.  If the interface requires you to do this, I
think the interface is flawed.

~j