Merge branch 'bc/hash-independent-tests-part-6'

Test updates to prepare for SHA-2 transition continues. * bc/hash-independent-tests-part-6: t4048: abstract away SHA-1-specific constants t4045: make hash-size independent t4044: update test to work with SHA-256 t4039: abstract away SHA-1-specific constants t4038: abstract away SHA-1 specific constants t4034: abstract away SHA-1-specific constants t4027: make hash-size independent t4015: abstract away SHA-1-specific constants t4011: abstract away SHA-1-specific constants t4010: abstract away SHA-1-specific constants t3429: remove SHA1 annotation t1305: avoid comparing extensions rev-parse: add a --show-object-format option t/oid-info: add empty tree and empty blob values t/oid-info: allow looking up hash algorithm name