Merge branch 'ma/sha1-is-a-hash'

Retire more names with "sha1" in it. * ma/sha1-is-a-hash: hash-lookup: rename from sha1-lookup sha1-lookup: rename `sha1_pos()` as `hash_pos()` object-file.c: rename from sha1-file.c object-name.c: rename from sha1-name.c