Re: [PATCH v2] cache-tree: do not lazy-fetch merge tree

Jeff King [off-list ref] writes:

I wondered also if this means we should be using OBJECT_INFO_QUICK.
I.e., do we expect to see a "miss" here often, forcing us to re-scan the
packed directory?

As a performance optimization hack, it is OK if we did not notice
that the tree object, which corresponds to what is currently
prepared for a directory in the index, does exist in the object
store.  It is not worth rescanning the packs to "protect" against
races, I think, in the "repair" codepath.

When the user actually wants to write the index out as a tree, we
would write it out as a loose object (or omit doing so if we know
there are already copies), but because it is not a crime to create a
duplicate loose object when we already have a packed copy, I do not
think we need to rescan in that context, either.  But I do not think
the codepath Jonathan's patch touches is about that operation.