[[!comment format=mdwn
 username="joey"
 subject="""comment 1"""
 date="2017-02-07T16:39:59Z"
 content="""
Such an env var could easily be supported.

It's desirable to mostly keep the mantainace of the git-annex branch
out of the user's view, because it's a complication that should not
need to worry about.

Keeping it in an env var does avoid complicating the discoverable
interface with some parameter to specify the commit message. Another
way would be to make the commit message configurable in git config.
Then it could be overridden with -c. Seems like the user of this 
feature is likely going to also use annex.alwayscommit=false sometimes
in order to construct git-annex branch commits that bundle up several
changes.

Anyway, I'm curious what kind of use cases make using custom commit
messages for the git-annex branch makes sense. I doubt that typical git
workflows with cherry-picking patches, patch review, etc, work with that
branch.
"""]]