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

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