Merge branch 'jc/retire-get-sha1-hex'

The implementation of "get_sha1_hex()" that reads a hexadecimal string that spells a full object name has been extended to cope with any hash function used in the repository, but the "sha1" in its name survived. Rename it to get_hash_hex(), a name that is more consistent within its friends like get_hash_hex_algop(). * jc/retire-get-sha1-hex: hex: retire get_sha1_hex()