Help: prefer commit hashes in commit references
The logic is that the describe output is readily available using git tag --contains locally. In addition, for a hypothetical commit which
landed in both v3.9.4 and v3.10.1, there is no "better" tag to refer to.
since v3.10.0's relation to such a commit is unclear either way.
Also mention that a Fixes trailer is preferred if the mention is just
to indicate a commit which introduced an error rather than writing a
complete sentence about it.
Thought it might be worth doing this in light of this week's Git Rev News where this covered.