* Reduce calls to git cat-file -s
There are multiple places where there are repeated calls to git cat-file
-s due to the blobs not being created with their size.
Through judicious use of git ls-tree -l and slight adjustments to the
indexer code we can avoid a lot of these calls.
* simplify by always expecting the long format
* Also always set the sized field and tell the indexer the update is sized
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