Ensure directories have trailing slashes in doLookupId()
- In the old days, stripping trailing slashes made sense as its useless
as it is and stripping it saved a bit of memory, but now with the
directories in the pool things are different: while not all paths
we'll see here necessarily exist in the pool already, NONE of them
exists without the trailing slash, so stripping it out wastes gobs
of memory. Simplifies the code a bit and saves several megs of memory
on larger transactions, what's not to like?