The current specification defines in informative section 6 that sha1 is the default algorithm although it clearly defines which algorithm are required in section 5.7.6.
Intention of this PR is putting focus on selecting best digest and keeping sha2 as common denominator as well as sha1 as backward compatibility requirement. So for the time being no change on requirement level but clearly indicating that things may change in the future. See e.g. section 5.2. of NIST SP800-107.
The current specification defines in informative section 6 that sha1 is the default algorithm although it clearly defines which algorithm are required in section 5.7.6.
Intention of this PR is putting focus on selecting best digest and keeping sha2 as common denominator as well as sha1 as backward compatibility requirement. So for the time being no change on requirement level but clearly indicating that things may change in the future. See e.g. section 5.2. of NIST SP800-107.